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Tricky Topics Flashcards

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Biology 101 flashcards
1
Q

Why are cells in meiosis during prophase II considered haploid?

A

Because they are sister chromatids, so there are only 23 chromosomes

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2
Q

How many times more genetic info is in a cell at prophase I than a gamete?

A

4 times the genetic information

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3
Q

Why is there twice the amount of genetic information in a cell at anaphase II than in the gametes?

A

Despite having 23 chromosomes, there are sister chromatids meaning there is more genetic info before it splits.

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4
Q

Where does RNA polymerase bind to on the operon? What conditions are required?

A

The RNA polymerase binds to the promoter region, however the promoter region sonly functional if the operon is ‘open’ and not repressed.

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5
Q

What is the active site and repressor site?

A

These are found on allosteric proteins (which are created by the regulatory gene, the repressor proteins are an example of an allosteric protein). The active site is where other chemicals can bind to induce conformational change, and the repressor site is where the protein itself binds to repress the promoter region on the operon

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6
Q

How does E. coli relate to tryptophan? Describe their relationship

A

Ecoli uses tryptophan to build proteins. If there is none, it will be ‘unhappy’. E coli levels will drop as tryptophan levels drop.

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7
Q

What mutation is it called when it scrambles the rest of the sequences?

A

A frameshift mutation

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8
Q

What is the first step when considering a DNA strand mutation?

A

Turn it into an mRNA strand in order to see the protein configurations / the resulting mutations

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9
Q

What is the ‘magic ratio’ for a dihybrid cross?

A

9:3:3:1

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10
Q

Who isolated the nuclein?

A

Miescher (Nuclein now known as DNA)

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11
Q

Who was responsible for discovering the molecular components of DNA replication?

A

Arthur Kornberg

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12
Q

Why does protein synthesis require energy?

A

ATP is required to bind the proteins to tRNA and GTP is required to make the ribosome function

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13
Q

What is the purpose of a polymerase chain reaction?

A

To amplify billions of copies of a target DNA sequence

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14
Q

What is needed for a polymerase chain reaction?

A

1) DNA extracted from the tissue of interest
2) Primers specific to the gene of interest (the target DNA sequences)
3) Heat stable DNA polymerase

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15
Q

How does one perform a polymerase chain reaction?

A
  • mix all components together
    1) denature at 95 degrees to separate strands
    2) Anneal at 60 degrees - allow primer to bind to the ends of the target DNA sequences
    3) Extent at 72 degrees - allow DNA polymerase to copy the target DNA sequences
  • repeat 30 times. each process doubles the number of copies.
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16
Q

How do you clone a gene using PCR, restrictions enzymes and plasmids

A
  • Amplify target sequences with PCR
  • Cut amplified target sequences and cloning plasmid with the same restriction enzymes
  • mix sequence and plasmid together and ligate (Creates recombinant plasmids which we inject into bacterial host cells - can survive against antibiotics due to antibiotic resistance gene)
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17
Q

What are transgenic animals?

A
  • deliberate introduction of genetic material into the zygote of an animals
  • gene introduced can be from same species or from another
  • allows for editing of specific traits by purposely altering the gene
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18
Q

What is pronuclear injection?

A
  • a form of transgenic animal
  • inject DNA into the nucleus to integrate that information
  • difficult to control copies
19
Q

What are gene knockouts?

A
  • Another kind of transgenic animal
  • target specific locus (gene targeting)
  • A single copy can be introduced or removed (can control number of copies, very versatile, very complicated)
20
Q

NOTE: in calculating single gene or multiple gene in a pedigree, take the ratio of affected children of heterozygous parents / total number of children OF THOSE SAME PARENTS
- also, don’t count the children of homozygous parents because they are not a good representation. Two recessive parents will obviously have recessive children.

A
21
Q

What is a clade?

A

A group which includes a single common ancestor and all descendants of that ancestor

22
Q

How quickly does adaptive radiation occur?

A

quickly, because after mass extinction many roles and adaptations to the new environment must be formed

23
Q

What is the endosymbiont theory?

A

states that the mitochondria and chloroplast in eukaryotic cells were once aerobic bacteria (prokaryote) that were ingested by a large anaerobic bacteria (prokaryote).
- this means that only eukaryotic would express this trait

24
Q

How did the genome of a plastid arise?

A

Plastids arose through an ancient event of endosymbiosis between a unicellular eukaryote host and a cyanobacterium symbiont. The DNA within the plastids of any living species of plant or alga is (thus) the highly reduced remnant of a cyanobacterial genome

25
Q

Which aspects of eukarya are most closely related?

A

Fungi and animals

26
Q

Does Darwin’s evolution have a direction?

A

There is no general direction for evolution, however it is assumed that each modification generally increases fitness (sexual selection may be an acceptation to this case)

27
Q

What is convergent evolution?

A

This is a form of analogy, where two species do not have a very common ancestor but evolve ‘side by side’ under similar conditions

28
Q

How are plasmids and mitochondria derived in eukaryotes?

A

Mitochondria and plastids are derived from proteobacteria
and cyanobacteria respectively by endosymbiosis

29
Q

Explain genetic drift

A

Genetic drift is not necessarily a mutation, it is just a change in allele frequency (bottleneck effect, founder effect) . Note that it may still be a genetic mutation!

30
Q

Why is genetic drift more significant in smaller populations?

A

The smaller population means a greater chance of having certain alleles removed. in a large population, a ‘loss’ of some alleles will not likely wipe out all of those alleles in a population, however in a smaller one that has the potential to entirely erase certain traits .

31
Q

What did Avery use in his experiments to purify DNA?

A
  • Avery used the enzyme lysate to remove the sugar coating and proteins
  • he used enzyme mixed with alcohol to remove RNA and DNA
32
Q

What do giesma stains bond to?

A

They bond to A-T bonds

33
Q

What synthesizes primers?

A

Primase

33
Q

What are the primary components of the DNA? Who discovered this?

A

Miescher isolated the nuclein and determined it to be composed of nitrogen, phosphorus, carbon, oxygen, and hydrogen.

34
Q

How do single gene disorders work?

A

Single-gene disorder is a disease caused by a known alteration or mutation in one of more than 20.000 genes in nearly every cell in the body.

35
Q

What are phages composed of? How is this helpful?

A

Composed of nucleic acids (DNA and RNA) and proteins
- when we make sulphur radioactive, shows that protein is not involved in transformation
- when we make phosphorus radioactive, shows that DNA is responsible for transformation ie: carries genetic information

36
Q

How are Ecoli related to tryptophan?

A

Ecoli uses tryptophan to create proteins so when tryptophan negative feedbacks itself, ECOLI levels drop .

37
Q

What are the causes of the different types of selections ?

A
  • stabilizing: two extremes ‘face off’ = balance
  • directional (classic response to changing environment)
  • disruptive (Intermediate phenotypes selected against, plays a role in some speciation)
38
Q

What is subfunctionalization?

A

An example of gene formation (gene duplication/ gene transfer) where gene has 2 functions and the splits so each has one

39
Q

What membrane do archaea have?

A

Plasma membranes

40
Q

What are the genes on the lac operon called ?

A

Lac Z, Lac Y, Lac A

41
Q

What is the name of the inducer protein on the lac operon?

A

Allactose

42
Q

What are the genes on the tryptophan operon?

A

Trp A, B, C, D, E

43
Q

Where did CRISPR come from?

A

From an Ecoli genome, allows us to find and fix or replace ‘bad’ genes using single guide RNA

bio (11 decks)

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