biology-class-12-unit-09-chapter-03-biologyin-human-welfare-human-health-and-disease-l-3-4-kycamg6epvi

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### <primary style="font-size:24px"> Think over </primary>
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| INNATE IMMUNITY|  | ACQUIRED IMMUNITY |
| -------- | -------- | -------- |
| Present since birth| | Develops during life time|
| Mainly conferred by various barriers viz physical, physiological or cytokine barriers| | Mainly conferred by lymphocytes (B & T cells)|
| It is non specific defense system | | Pathogen specific|
| | | Has memory|

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<footer style = "font-size: 18px">Human health and disease $\rightarrow$ Think over $\rightarrow$ <span style = "color:blue"> Think over </span> $\rightarrow$ Think over $\rightarrow$ Think over </footer>

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| CYTOKINES|  | LYSOZYME|
| -------- | -------- | -------- |
| Produced mostly by cells of immune system like the leukocytes| | Type of physiological barrier, present in tears, saliva, mucus etc|
| Mainly act against viral infections| | Mainly acts against invading bacteria|

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<footer style = "font-size: 18px">Think over $\rightarrow$ Think over $\rightarrow$ <span style = "color:blue"> Think over </span> $\rightarrow$ Think over $\rightarrow$ Aquired immuno deficiency syndrome </footer>

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### <primary style="font-size:24px"> Aquired immuno deficiency syndrome </primary>
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- **Aquired** Obtained/ Developed

- **Immuno deficiency** Deficiency of immunity

- **Syndrome** A group of symptoms which consistently occur together

![image](/subject-images/iitpal/image/biology-class-12-unit-09-chapter-03-biologyin-human-welfare-human-health-and-disease-l-3_4-kycamg6epvi-036-0465.6.jpg)

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<footer style = "font-size: 18px">Think over $\rightarrow$ Think over $\rightarrow$ <span style = "color:blue"> Aquired immuno deficiency syndrome </span> $\rightarrow$ A brief history Of aids $\rightarrow$ How HIV spreads </footer>

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### <primary style="font-size:24px"> A brief history Of aids </primary>
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- **Simion immunodeficiency virus(SIV) was present in chimpanzee**

- **It was transmitted to humans and mutated into HIV when humans hunted chimpanzees for meat and came into contact with their infected blood**

- **The earliest known case of infection with HIV -1 in a human was detected in Congo**

- **Term AIDS came to existence, to describe the occurrence of opportunistic infection like, Kaposi's sarcoma, and** _pneumocystis jirovecii_ **pneumonia in previously healthy people**

- **Virus that causes AIDS** was discovered it was named **HTLV-III/ LAV (human T-cell Lymphootropic virus type III/ lymphadenopathy associated virus)**

- **Later the name was changed to HIV**

- **More than 70 million people have been infected with the HIV virus and about 35 million people have died of HIV**

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<footer style = "font-size: 18px">Think over $\rightarrow$ Aquired immuno deficiency syndrome $\rightarrow$ <span style = "color:blue"> A brief history Of aids </span> $\rightarrow$ How HIV spreads $\rightarrow$ SALIVA AND HIV </footer>

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### <primary style="font-size:24px"> How HIV spreads </primary>
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- **Through body fluids:**

- Blood

- Semen/vaginal fluids

- Mother's milk

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<footer style = "font-size: 18px">Aquired immuno deficiency syndrome $\rightarrow$ A brief history Of aids $\rightarrow$ <span style = "color:blue"> How HIV spreads </span> $\rightarrow$ SALIVA AND HIV $\rightarrow$ SALIVA AND HIV </footer>

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### <primary style="font-size:24px"> SALIVA AND HIV </primary>
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- Although HIV can be detected in saliva, it can't be passed to other people through saliva (sharing food and drinks) because a combination of **antibodies and enzymes** found naturally in saliva prevent **HIV from infecting new cells**

- Whole saliva protects susceptible cells against HIV infection Some of the inhibitory components in oral secretions are

- **HIV-specific antibodies** neutralise and inactivate virus

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<footer style = "font-size: 18px">A brief history Of aids $\rightarrow$ How HIV spreads $\rightarrow$ <span style = "color:blue"> SALIVA AND HIV </span> $\rightarrow$ SALIVA AND HIV $\rightarrow$ Why does aids not spread through casual contact/objects </footer>

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### <primary style="font-size:24px"> Structure of HIV </primary>
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- **Envelope**

- Composed of the lipid lilayer taken from the **human cell**
- Also contains proteins from the host cell and relatively few copies of the HIV Envelope protein

- **Capsid**

- Capsid is composed of viral protein
- The ssRNA in tightly bound to nnucleocapsid proteins and enzymes needed for the development of the virion

- **Genome**
- Retrovirus, RNA genome
- 2 copies of ssRNA, code for the virus's nine genes

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<footer style = "font-size: 18px">SALIVA AND HIV $\rightarrow$ Why does aids not spread through casual contact/objects $\rightarrow$ <span style = "color:blue"> Structure of HIV </span> $\rightarrow$ Replication of hiv in human cells $\rightarrow$ Stages of HIV Infection </footer>

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### <primary style="font-size:24px"> Stages of HIV Infection </primary>
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- **Acute HIV infection stage**

- HIV ifvection, flu-like symptoms many аррear Large amounts of virus are being produced in the body

- The virus unes _CD4 cell_ to replicate and destroys them in the process. Became of this, _CD4-count_ can fall rapidly (In a healthy immune system, CD4-counts are between 500 and 1,000 cells/mm3)

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<footer style = "font-size: 18px">Structure of HIV $\rightarrow$ Replication of hiv in human cells $\rightarrow$ <span style = "color:blue"> Stages of HIV Infection </span> $\rightarrow$ Stages of HIV Infection $\rightarrow$ Stages of HIV Infection </footer>

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- **Clinical latency stage/chronic infection**

- People experience **no symptoms**, or only mild ones

- The **HIV** continues to **reproduce at very low levels, although** it is still active for people who are not on ART, the clinical Latency stage lasts an average of 10 years

- **AIDS**

- This is the stage of HIV infection that occurs when the immune system is badly damaged and people become vulnerable to _opportunistic infections_

- When the number of CD4 cells falls below 200 cells/mm3 af blood, the person is considered to have progressed to AIDS Without treatment, people who progress to AIDS typically survive about 3 years

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<footer style = "font-size: 18px">Replication of hiv in human cells $\rightarrow$ Stages of HIV Infection $\rightarrow$ <span style = "color:blue"> Stages of HIV Infection </span> $\rightarrow$ Stages of HIV Infection $\rightarrow$ Tools for diagnosis ELISA </footer>

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### <primary style="font-size:24px"> Tools for diagnosis ELISA </primary>
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- A common test used to detect if a patient has been exposed to a virus such as HIV or Dengue,

- This test takes advantage of the interactions between antigens and antibodies

- If an ELISA (Enzyme Linked Immuno Sorbent assay) test is positive, the Western blot test is usually administered to confirm the diagnosis

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<footer style = "font-size: 18px">Stages of HIV Infection $\rightarrow$ Stages of HIV Infection $\rightarrow$ <span style = "color:blue"> Tools for diagnosis ELISA </span> $\rightarrow$ Steps of ELISA $\rightarrow$ Steps of ELISA </footer>

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- Antibody binds to well

- Sample added if antigen is present, binding occurs

- Another antibody with chromogenic compound added

- If binding ocurs, colour will be produce

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<footer style = "font-size: 18px">Stages of HIV Infection $\rightarrow$ Tools for diagnosis ELISA $\rightarrow$ <span style = "color:blue"> Steps of ELISA </span> $\rightarrow$ Steps of ELISA $\rightarrow$ Treatment of AIDS </footer>

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- ELISA is quite sensitive in chronic HIV infection, but because antibodies aren't produced immediately upon infection, one may test negative during a window of a few weeks to a few months after being infected

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<footer style = "font-size: 18px">Tools for diagnosis ELISA $\rightarrow$ Steps of ELISA $\rightarrow$ <span style = "color:blue"> Steps of ELISA </span> $\rightarrow$ Treatment of AIDS $\rightarrow$ Prevention </footer>

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- The human body can't get rid of HIV completely, even with treatment
- Antiretroviral therapy (**ART**) is used to control HIV, ART medicines prevent HIV from multiplying
- If left untreated HIV will attack the immune system and eventually progress to **AIDS**
- HIV medicines are grouped into six drug classes according to how they fight HIV
- <ins>The six drug classes are</ins>

- Non-nudeoside **reverse transcriptase inhibitors** (NNRTIs)
- Nucleoside reverse transcriptase inhibitors (NRTIS)

- **Protease inhibitors (PIs)**
 - **Fusion inhibitors**

- CCR5 antagonists (CCR5s) (also called **entry inhibitors**)
- Integrase **strand transfer inhibitors** (INSTIs)

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<footer style = "font-size: 18px">Steps of ELISA $\rightarrow$ Steps of ELISA $\rightarrow$ <span style = "color:blue"> Treatment of AIDS </span> $\rightarrow$ Prevention $\rightarrow$ Prevention </footer>

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### <primary style="font-size:24px"> What is CANCER </primary>
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- **Cancer is a class of diseases characterized by out-of-control cell growth**  
 - Cancer harms the body when **altered cells divide uncontrollably to form lumps** or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream)
 - Tumors can grow and **interfere** with the digestive, nervous, and circulatory systems, and they can release hormones that alter body function

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<footer style = "font-size: 18px">Prevention $\rightarrow$ Prevention $\rightarrow$ <span style = "color:blue"> What is CANCER </span> $\rightarrow$ CANCER $\rightarrow$ TYPES OF TUMORS </footer>

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### <primary style="font-size:24px"> CANCER </primary>
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* Normally, human cells grow and divide to form new cells as the body needs them When cells grow old or become damaged, they die, and new cells take their place

* When cancer develops, however, this orderly process breaks down. As cells become more and more abnormal, **old or damaged cells survive when they should die, and new cells form when they are not needed**

* These extra cells can divide without stopping and may form growths called tumors

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<footer style = "font-size: 18px">Prevention $\rightarrow$ What is CANCER $\rightarrow$ <span style = "color:blue"> CANCER </span> $\rightarrow$ TYPES OF TUMORS $\rightarrow$ WHEN CANCER SPREADS METASTASIS </footer>

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### <primary style="font-size:24px"> WHEN CANCER SPREADS METASTASIS </primary>
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- A cancer that has spread from the place where it first started to another place in the body is called **metastatic cancer**.

- In metastasis, cancer cells break away from where they first formed (**primary cancer**), travel through the blood or lymph system, and form new tumors (**metastatic tumors**) in other parts of the body

- Metastatic cancer has the same name and the same type of cancer cells as the original, or primary, cancer

- For example, breast cancer that spreads to and forms a metastatic tumor in the lung is metastatic breast cancer, not lung cancer

- Metastatic tumors can cause **severe damage** to the body functions, and most people who die of cancer die of metastatic disease

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<footer style = "font-size: 18px">CANCER $\rightarrow$ TYPES OF TUMORS $\rightarrow$ <span style = "color:blue"> WHEN CANCER SPREADS METASTASIS </span> $\rightarrow$ CANCER CELLS vs NORMAL CELLS $\rightarrow$ TYPES OF CANCER </footer>

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- Cancer cells do not show **contact inhibition**

- They are **less specialized** than normal cells. This is one reason that, unlike normal cells, cancer cells continue to divide without stopping

- Cancer cells are able to ignore signals that normally tell cells to stop dividing or that begin **programmed cell death**, or **apoptosis**

- Cancer cells may be able to influence the normal cells, molecules, and blood vessels that surround and **feed a tumor**

- Cancer cells are also often able to **evade the immune system**

- In general, cancer cells have more genetic changes, i.e **mutations** in DNA, than normal cells

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<footer style = "font-size: 18px">TYPES OF TUMORS $\rightarrow$ WHEN CANCER SPREADS METASTASIS $\rightarrow$ <span style = "color:blue"> CANCER CELLS vs NORMAL CELLS </span> $\rightarrow$ TYPES OF CANCER $\rightarrow$ HOW CANCER ARISES </footer>

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### <primary style="font-size:24px"> TYPES OF CANCER </primary>
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- Carcinoma, Sarcoma
- Leukemia, Lymphoma
- Multiple Myeloma, Melanoma
- Brain and Spinal Cord Tumors
- Epithelial Cells
- Connective tissue
- Bone marrow
- Lymphocytes
- Plasma Cells
- Melanocytes

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<footer style = "font-size: 18px">WHEN CANCER SPREADS METASTASIS $\rightarrow$ CANCER CELLS vs NORMAL CELLS $\rightarrow$ <span style = "color:blue"> TYPES OF CANCER </span> $\rightarrow$ HOW CANCER ARISES $\rightarrow$ Causes of cancer </footer>

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### <primary style="font-size:24px"> HOW CANCER ARISES </primary>
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- Cancer is caused by **changes to genes** that control the way our cells function, especially how they grow and divide

- This happens because of **mutations** in the DNA. These mutations can cause the cell to stop its normal function and may allow a cell to become cancerous

- Each person's cancer has a unique combination of mutations

- As the cancer continues to grow, additional changes will occur Even within the same tumor, different cells may have different genetic changes

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<footer style = "font-size: 18px">CANCER CELLS vs NORMAL CELLS $\rightarrow$ TYPES OF CANCER $\rightarrow$ <span style = "color:blue"> HOW CANCER ARISES </span> $\rightarrow$ Causes of cancer $\rightarrow$ Drivers of cancer </footer>

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<footer style = "font-size: 18px">TYPES OF CANCER $\rightarrow$ HOW CANCER ARISES $\rightarrow$ <span style = "color:blue"> Causes of cancer </span> $\rightarrow$ Drivers of cancer $\rightarrow$ Chemical carcinogens </footer>

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### <primary style="font-size:24px"> Drivers of cancer </primary>
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- Proto- oncogenes

- Tumor suppressor genes

- DNA repair genes

- Involved in normal cell growth and division

- DNA repair genes are involved in fixing damaged DNA

- Allow rapid growth Fail to stop uncontrolled cell growth Make mistakes when repairing DNA errors

- Cells with mutations in these genes tend to develop additional mutations in other genes

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<footer style = "font-size: 18px">HOW CANCER ARISES $\rightarrow$ Causes of cancer $\rightarrow$ <span style = "color:blue"> Drivers of cancer </span> $\rightarrow$ Chemical carcinogens $\rightarrow$ Chemical carcinogens </footer>

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### <primary style="font-size:24px"> Chemical carcinogens </primary>
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- Several chemicals and environmental toxins are responsible for changes in normal cellular DNA.  
 - Substances that cause DNA mutations are known as **mutagens**, and mutagens that cause cancers are known as **carcinogens**
 - **Tobacco** smoking is associated with many forms of cancer, and causes 90% of lung cancer

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<footer style = "font-size: 18px">Causes of cancer $\rightarrow$ Drivers of cancer $\rightarrow$ <span style = "color:blue"> Chemical carcinogens </span> $\rightarrow$ Chemical carcinogens $\rightarrow$ Ionizing Radiations </footer>

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- Tobacco is also related to other cancers such as lung, larynx, head, neck, stomach, bladder, kidney, oesophagus and pancreas as it contains other known carcinogens, including **nitrosamines and polycyclic aromatic hydrocarbons**.  
 - Similarly, prolonged exposure to **asbestos fibers** is associated with mesothelioma.  
 - **Alcohol**  
 - **Many day to day items like dyes, paints, air fresheners, anti prespirants also carry a host of carcinogens**

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<footer style = "font-size: 18px">Drivers of cancer $\rightarrow$ Chemical carcinogens $\rightarrow$ <span style = "color:blue"> Chemical carcinogens </span> $\rightarrow$ Ionizing Radiations $\rightarrow$ OTHER CAUSES </footer>

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### <primary style="font-size:24px"> Ionizing Radiations </primary>
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- Radiations due to **radon gas** and prolonged exposure to **ultraviolet radiation** from the sun can lead to **melanoma** and other skin malignancies.

- **Radiation therapy** given for one type of cancer may also cause another type of cancer. For example, those who receive chest radiation therapy for lymphomas may later develop breast cancer

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<footer style = "font-size: 18px">Chemical carcinogens $\rightarrow$ Chemical carcinogens $\rightarrow$ <span style = "color:blue"> Ionizing Radiations </span> $\rightarrow$ OTHER CAUSES $\rightarrow$ OTHER CAUSES </footer>

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### <primary style="font-size:24px"> OTHER CAUSES </primary>
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- **Viral and bacterial infections**

- Some cancers can be caused by infections with pathogens Example **liver cancers due to Hepatitis B and C infections**

- Cervical cancer due to infections with Human Papilloma virus (HPV)

- Epstein Barr virus causing Burkitt's lymphoma

- Gastric cancer due to Helicobacter pylori infection

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<footer style = "font-size: 18px">Chemical carcinogens $\rightarrow$ Ionizing Radiations $\rightarrow$ <span style = "color:blue"> OTHER CAUSES </span> $\rightarrow$ OTHER CAUSES $\rightarrow$ CANCER DETECTION & DIAGNOSIS </footer>

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### <primary style="font-size:24px"> Reflection Imaging </primary>
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- It is produced by sending high-frequency sounds to the body part or organ being studied

- These sound waves "bounce" off of the various types of body tissues and structures at varying speeds, depending on the density of the tissues present

- The bounced sound waves are sent to a computer that analyzes the sound waves and produces a visual image of the body part or structure

- Example Ultrasound

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<footer style = "font-size: 18px">DIAGNOSTIC IMAGING $\rightarrow$ DIAGNOSTIC IMAGING $\rightarrow$ <span style = "color:blue"> Reflection Imaging </span> $\rightarrow$ Emission Imaging $\rightarrow$ Endoscopic Examinations </footer>

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### <primary style="font-size:24px"> Emission Imaging </primary>
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- Emission imaging occurs when tiny nuclear particles or magnetic energy are detected by a scanner and analyzed by computer to produce an image of the structure or organ being examined

- **Magnetic resonance imaging** (MRI) uses radio waves with a machine that creates a strong magnetic field that in turn causes cells to emit their own radio frequencies

- **Gadolinium** is injected into a veins It collects around cancer cells so they show up brighter in the picture

- MRI may be used instead of a CT scan in situations where organs or soft tissue are being studied, because with MRI scanning bones do not obscure the images of organs and soft tissues, as does CT scanning

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<footer style = "font-size: 18px">DIAGNOSTIC IMAGING $\rightarrow$ Reflection Imaging $\rightarrow$ <span style = "color:blue"> Emission Imaging </span> $\rightarrow$ Endoscopic Examinations $\rightarrow$ DIRECT DNA STUDIES </footer>

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### <primary style="font-size:24px"> DIRECT DNA STUDIES </primary>
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- **Direct DNA studies** simply look directly at the gene in question for mutations
 - Mutations in the DNA may include a replication of the gene's DNA (duplication)  
 - A loss of a piece of the gene's DNA (deletion)  
 - An alteration in a base pair of the gene's DNA (point mutation),  
 - Or the repeated replication of a small sequence of the gene's DNA (repeats)  
 - Firstly, the mutation present in a family is studied, by studying the family member with cancer 
 - Afterwards, other family members can choose to have testing for the mutation to determine if they have an increased risk to develop certain cancers and to pass the mutation on to the next generation

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<footer style = "font-size: 18px">Emission Imaging $\rightarrow$ Endoscopic Examinations $\rightarrow$ <span style = "color:blue"> DIRECT DNA STUDIES </span> $\rightarrow$ Direct DNA studies for Cancer Detection $\rightarrow$ INDIRECT DNA STUDIES </footer>

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### <primary style="font-size:24px"> Direct DNA studies for Cancer Detection </primary>
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- DNA of the cancer patient screened for mutations

- $\downarrow$

- Mutations Associated with Cancer Detected

- $\downarrow$

- Radio labelled probe made with mutated gene

- $\downarrow$

- Hybridization with DNA to be tested

-  Positive (Susceptible)

-  Negative

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<footer style = "font-size: 18px">Endoscopic Examinations $\rightarrow$ DIRECT DNA STUDIES $\rightarrow$ <span style = "color:blue"> Direct DNA studies for Cancer Detection </span> $\rightarrow$ INDIRECT DNA STUDIES $\rightarrow$ Indirect DNA studies for cancer detection. </footer>

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### <primary style="font-size:24px"> INDIRECT DNA STUDIES </primary>
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* Indirect DNA studies involve using "**markers**" to find out whether a person has inherited the crucial region of the genetic code that is passing through the family with the disease

* Markers are DNA sequences located close to or even within the gene of interest

* Because the markers are so close, they are almost always inherited together with the disease i.e they are "linked"

* If someone in a family has the same set of linked markers as the relative with the disease, this person often also has the disease- causing gene mutation
- Because indirect DNA studies involve using linked markers, these types of studies are also called linkage studies

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![alt text](https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/1d130b95-2dd8-4a14-6b90-090c63dffd00/public)

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<footer style = "font-size: 18px">DIRECT DNA STUDIES $\rightarrow$ Direct DNA studies for Cancer Detection $\rightarrow$ <span style = "color:blue"> INDIRECT DNA STUDIES </span> $\rightarrow$ Indirect DNA studies for cancer detection. $\rightarrow$ TUMOR BIOPSIES </footer>

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### <primary style="font-size:24px"> TUMOR BIOPSIES </primary>
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- A biopsy is a procedure performed to remove tissue or cells from the body for examination under a microscope
- Biopsies are usually performed to determine whether a tumor is malignant (cancerous) or to determine the cause of an unexplained infection or inflammation.

- The following are the most commmmon types of biopsies
- Endoscopic biopsy
- Bone marrow biopsy
- Excisional or incisional biopay
- Fine needle aspiration biopsy
- Punch biopsy
- Shave biopsy
- Skin

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<footer style = "font-size: 18px">INDIRECT DNA STUDIES $\rightarrow$ Indirect DNA studies for cancer detection. $\rightarrow$ <span style = "color:blue"> TUMOR BIOPSIES </span> $\rightarrow$ TREATMENTS $\rightarrow$ CHEMOTHERAPY </footer>

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### <primary style="font-size:24px"> CHEMOTHERAPY </primary>
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- The use of anticancer **drugs to shrink or kill cancerous cells** and reduce cancer spreading to other parts of the body

- Chemotherapy drugs are very effective at stopping cancer cells from growing and proliferating, but they also inadvertently target healthy cells that frequently replicate and replace themselves 
- That includes cells in the Mouth, Skin, Hair, Bone marrow, Intestines, Reproductive system

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![image](/subject-images/iitpal/image/biology-class-12-unit-09-chapter-03-biologyin-human-welfare-human-health-and-disease-l-3_4-kycamg6epvi-248-3202.8.jpg)

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<footer style = "font-size: 18px">TUMOR BIOPSIES $\rightarrow$ TREATMENTS $\rightarrow$ <span style = "color:blue"> CHEMOTHERAPY </span> $\rightarrow$ CHEMOTHERAPY $\rightarrow$ Radiation Therapy </footer>

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### <primary style="font-size:24px"> CHEMOTHERAPY </primary>
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- Most side effects show up in the days or weeks following treatment and go away soon after it ends But there's a chance some show up much later, take longer to go away or become permanent

- **Radiation Therapy**

- The use of high-energy radiation to kill or shrink cancer cells, tumors, and non-cancerous diseases
 - Radiation therapy works by damaging the genes of cancer cells so they stop growing and dividing, eventually dying off
 - Some healthy cells do get caught up in the process, the death of these cells leads to side effects

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<footer style = "font-size: 18px">TREATMENTS $\rightarrow$ CHEMOTHERAPY $\rightarrow$ <span style = "color:blue"> CHEMOTHERAPY </span> $\rightarrow$ Radiation Therapy $\rightarrow$ SURGERY </footer>

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### <primary style="font-size:24px"> Radiation Therapy </primary>
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- **Immunotherapy**

- Immunotherapy is designed to boost the body's immune system in order to fight cancer

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<footer style = "font-size: 18px">CHEMOTHERAPY $\rightarrow$ CHEMOTHERAPY $\rightarrow$ <span style = "color:blue"> Radiation Therapy </span> $\rightarrow$ SURGERY $\rightarrow$ Other Treatments </footer>

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### <primary style="font-size:24px"> Other Treatments </primary>
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- **Hormone therapy**

* Use of supplemental hormones to prevent or stop the growth or spread of tumors The type of hormone therapy used depends upon the type and size of the tumor, age, the presence of hormone receptors on the tumor, etc

- **Blood and bone marrow transplant**

* A specialized therapy to transfer healthy bone marrow cells into a patient after their own unhealthy bone marrow has been eliminated

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![image](/subject-images/iitpal/image/biology-class-12-unit-09-chapter-03-biologyin-human-welfare-human-health-and-disease-l-3_4-kycamg6epvi-254-3255.6.jpg)

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<footer style = "font-size: 18px">Radiation Therapy $\rightarrow$ SURGERY $\rightarrow$ <span style = "color:blue"> Other Treatments </span> $\rightarrow$ Other Treatments $\rightarrow$ Think over </footer>

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### <primary style="font-size:24px"> Think over </primary>
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- 1. From the chapter, can you find one example which supports the presumption of the "RNA world"?

- 2. Analyze the difference between being HIV positive and having AIDS

- 3. From our discussions on AIDS, can you infer, which barriers of immunity are impervious to the HIV, while which are easily broken?

- 4. How do ARTs help HIV infected persons to lead a normal and prolonged life? Can a HIV+ person still transmit HIV, if he/she is on ARTs?

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<footer style = "font-size: 18px">Other Treatments $\rightarrow$ Other Treatments $\rightarrow$ <span style = "color:blue"> Think over </span> $\rightarrow$ Thank you $\rightarrow$  </footer>