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viruses Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

DNA viruses

A

The genetic material is DNA.
The viral DNA acts as a template for both new viral DNA and for the mrnas needed to induce synthesis of viral proteins for exmaple lambda phage

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2
Q

RNA viruses

A

RNA is the genetic material.
RNA viruses do not produce DNA as part of their life.
The majority of RNA viruses contain a single strand of rna known as ssrna

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3
Q

Positive ssrna

A

Has RNA that can directy act as MRNA and be translated at the ribosomes.
E.G tobacco mosaic virus

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4
Q

Negative ssrna

A

Cannot be directly translated. The rna strand muust be trasncribed before it is trasnlated at the ribosome.
E.G Ebola

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5
Q

RNA retrovirus

A

Have a protein caspid and a lipid envelope. Single strand of viral RNA dircts the synthesis of reverse transcriptase. This goes on to make DNA molecules corresponding to teh viral genome. This DNA is then incorporated into the host cell DNA and used as a template for new viral proteins and a new viral RNA genome

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6
Q

Outline the lytic cycle of a virus

A

Viral RNA is injected in cilliated epithelial cell. Virl RNA hijacks cell biochemistry, producing virions. The cell lysis releasing teh virions.

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7
Q

Outline Latency

A

Lysogenic virus injects viral DNA in the form of provirus into the host cells DNA allowing it to replicate every tme cell divides. The provirus can remian dormant if the virus produces repressor proteins, preventing mRNA from being produced by mking it impossible to trnslate the rest of teh viral genetc material. During this period of lysogeny, when thevirus is part of the reproducing host cell, the virus is latent.

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8
Q

How do antivirals work?

A

Know that viruses are not living cells and so antivirals must work by inhibiting
virus replication.

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9
Q

Ethical implications of drug testing

A

Some people feel that it is not ethical to use untested drugs not completed through full human trials
If an untested drug produces unexpected side effect it can make teh situation worse
Decidign who takes the drug is ddificult
Informed onsent is difficult: Depends on a evel ofeducation to understand the durg
Issues of trust between indivudlas, communites and helath workers

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10
Q

How do antivirals treat viral infections/ target virus replication

A

Target receptors by which viruses recognise their host cells
Target enzymes which translate or replicate the viral DNA/RNA
Inhibit protease enzymes which enable new virus particles to bud from host membranes

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11
Q

How to control disease

A

Rapid identification of the disease by effective testing
Isolation
Preventing transmission from one individual to another: hand washing
Sterilising and disposal of equipment and bedding: main transmission cause of Ebola.
PPE: protective clothing.
Identifying contacts – monitor/treat/rapidly isolate.

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12
Q

Define the cell cycle

A

a regulated process in which cells divide into two
identical daughter cells, and that this process consists of three main stages:
interphase, mitosis and cytokinesis.

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13
Q

Give another explanation lysogenic cycle

A

The retrovirus attacks an animal cell
Virus RNA enters the host cell. This RNA cannot be used as mRNA.
Viral RNA is trasnlated into viral DNA by reverse transcriptase in the cytoplasm
Viral DNA is incorporated into teh host DNA in the nucleus. It directs the production of new viral genome RNA, mRNA and coat proteins
New viral proteins are assembled and leave teh host cell by exocytosi. Viral DNA remains in the nucleus so teh process is repeated

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14
Q

How does a virus work?

A

Viruses only reproduce inside a living cell.

To do this the virus must first enter the cell through
the plasma membrane and (if present) the cell wall.

Viruses do so by either attaching to a receptor on the
cell’s surface or by simple mechanical force.

The virus then releases its genetic material (DNA or
RNA) into the cell.

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15
Q

How do DNA viruses work?

A

Lytic cycle

Lysogenic cycle

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16
Q

Ethical implications when fast tracking drugs

A

Severity of diseases
Availability of other treatments
Effectiveness of standard disease control measures
Transparency of the process and informed consent of those given the treatment
Freedom of choice
Involvement of the affected community.
Clear clinical data of the new medicines and on-going assessments of safety and efficacy.

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17
Q

Interphase

A

A period of non division when the cells increase in size and mass, carry out normal cellular actvities and replicae their DNA ready for division

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18
Q

Mitosis

A

The process by which a cell divides to produce two gentically identical daughter cells

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19
Q

Cytokinesis

A

Division of the cytoplasm at teh en dof mitosis to form two geneticlly idenitcal cells

20
Q

Why are viruses non living

A

Viruses are not living becuase they are acellular which means they have no cytoplasm, no metabolism and no self replicating

Viruses have no metabolism = difficult to treat infection after initial contact.

21
Q

G1

A

Time between the end of the previous round of mitosis and the start of chromosome duplication. Cell assimilates material, grows and develops. This may also involve duplicating organelles and making proteins

22
Q

G1 simpler terms

A

ATP is produced for the energy intensive process of cell division about to occur

23
Q

S

A

Chromosomes replicate and become double stranded chromatids (this happens at the end) This also involves DNA synthesis where the strands of the DNA is replicated and genome is doubled. The DNA is being doubled so that each of the new cells will have its own set of DNA

24
Q

S simpler terms

A

The genetic material is copied

Chromosomes replicate and become double stranded chromatids

25
Q

G2

A

G2: This is the time where all the organelles and other materials needed for cell division is synthesised (two of each organelle). The organelles begin to divide. It starts to condense the genetic material

26
Q

G2 simpler terms

A

The organelles duplicate
More cytoplasm is produced as the cell grows further ready for division
DNA is checked for errors

27
Q

What is teh cyclins

A

Cyclins: Involved in the control of the cell cycle by their attachment to cyclin dependant kinases.

28
Q

What happens to teh cell mass as the cell cycle progresses

A

The mass of the cell will increase during the cell cycle as it makes more proteins, organelles and DNA.

29
Q

What is teh role of mitosis

A

Growth
Repair
Aesexual reproduction

30
Q

How is mitosis involved in growth

A

Growth: Mitosis is the splitting of cells. It increases the number of cells within your body which enables you to grow

31
Q

How is mitosis involvwdin repair

A

When part of a tissue breaks, then there are cells lost. So, mitosis will create tons of new cells in periods of time to fill the gap and make the tissue bigger again. This ensures that the tissue is back to normal and can function properly. It’s like a wound healing.

32
Q

How is mitosis involedin aesexual reproduction

A

Asexual reproduction uses the process of mitosis to create the identical copies (clones) of the parent cell. It therefore leads to offspring that show no genetic variation. It shares the genetic material of the parent cell between the two daughter cells.

33
Q

Sporulation

A

Involes mitosis and teh prouctionofaesexual spores that re capableof growing itn o new indviduals
They can survive harmful conditions

34
Q

Regeneration

A

Organisms replacing lost body parts

35
Q

Fragmentation

A

The use of mitosis to regenerate whole organism from a fragment of teh original

36
Q

Budding

A

The production by mitosis of an outgrowth fromt he parent organism that devlops into a small independt organism

37
Q

Vegetaive propagation

A

The process by which a plant forms a strcuture by mitosis that devlops ito a fully differentiated genetically idneitcla new pant

38
Q

Parthenogenesis

A

The process by which an unfertilised egg cell develops into a new individuals

39
Q

Mitosis in plants

A

Takes plae at teh meristem

Just behin teh tip of teh steem and the root where the cell continuously divide actvily

40
Q

Prophase

A

Chromosomes arecoieup ad onsst of two daughter chromatids joined by a centromere. The nucelolus breaks down and the nucear envelope dissappers.
Spindle fibre forms

41
Q

Metaphase

A

Chromosome line up on teh metaphase platen

42
Q

Anaphase

A

Centromeres split so chromatids become new chromosomes. They are moved to opposite poles of cells, centromere first, by contraction of the spindle fibre

43
Q

Telophase

A

Nuclear memrbne forms around two sets fo chromsoes, chromosomes unravela dn teh spinle fibre breaks down

44
Q

First phase of meisosi

A

Prophase 1: Each chromosomes appears in condensed form with two chromatids. Homologous pairs of chromosomes associate with each other. Crossing over occurs

Metaphase: Spindle fibre forms and pairs of chromosomes line up on metaphase plate

Anaphase; Centomeres dont divide. One chromosome from each homologous pairs moves to each end of the cell. As a result, the chromosoome number in each cell is half the original

Telophase: Nuclear membrane reforms and cells begin to divide.

45
Q

Second phase of meiosis

A

Prophase 2: New spindles form

Metaphase: Chromosomes line up on metaphase plate

Anaphase: Centromeres divide and chromatids move to opposite ends of the cell

Telophase: Nuclear envelope reforms, chromosomes return to their interphase state and cytokinesis happens

Four daughter cells with half the chromosome number of the original diploid cell.

The four daughter cells are h aploid as they contain half the number of chromosome of teh diploid parent cell.

46
Q

How does meiosis result in genetic variation

A

Crossing over and idenpendent asortment

Biology (2 decks)

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