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Biology 1 Exam 3 > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

During mitosis, when do the sister chromatids become daughter chromosomes?

A

Anaphase. During anaphase, centromeres split, and sister chromatids are pulled by the spindle fibers toward opposite poles of the cell to become daughter chromosomes.

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2
Q

Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?

A

G1 checkpoint. It would need to make sure that there is enough nutrients, big enough cell size, social signals are present, DNA is undamaged for it to pass. If it does not pass, it goes to G0 state (like mature cells).

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3
Q

What stage of cell replication will be affected by a drug inhibiting shortening of microtubules?

A

Anaphase. ***

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4
Q

Why do neurons and some other specialized cells divide infrequently?

A

Stuck in G0 phase for a while because they are differentiated (due to cell signals)***

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5
Q

During which process does independent assortment of chromosomes occur?

A

Metaphase 1 sets up crossing over where it separates at Anaphase 1

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6
Q

When does the nuclear membrane disappear during cell division?

A

Prophase

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7
Q

Which protein moves chromosomes following their attachment of spindle microtubules?

A

kinetechores

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8
Q

How is metaphase characterized?

A

Sister chromosomes lining up in the at the metaphase plate and all the spindle fibers are lined up there

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9
Q

Which cytoskeletal proteins are involved in animal cell cytokinesis?

A

Actin and Myosin( pinches cell and creates cleavage furrow)

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10
Q

What happens to MPF once a cell completes mitosis?

A

During anaphase, an enzyme complex begins degrading MPF’s cyclin
subunit. MPF triggers a chain of events that leads to its own destruction. Phosphates wont be attached after mitosis completes so concentration decreases.

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11
Q

If M-phase checkpoint fails to happen, in which stage of mitosis would the cells be most

A

Metaphase

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12
Q

What happens to cell cycle progression if a cell has accumulated DNA damage?

A

If the DNA is physically damaged, the p53 protein either pauses the cell cycle(G1), or initiates apoptosis; programmed cell death

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13
Q

What are tumor suppressor proteins?

A

p53 is an example of a tumor suppressor; intitates apoptosis and makes sure destorys damaged cells. Damage to the p53 gene can
lead to uncontrolled cell division

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14
Q

What are haploidy and diploidy?

A

haploidy (n) is the amount of distinct chromosomes that one person is supposed to have while diploidy (2n) is two times the amount of each chromosomes present.

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15
Q

What is aneuploidy?

A

It is an abnormal amount of chromosomes that a person has (humans have 46 but aneuploidy has 43)

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16
Q

When chromosome crossover takes place?

A

Late Prophase 1

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17
Q

When does the synaptonemal complex disappear during meiosis?

A

late prophase of meiosis I

18
Q

What are homologous chromosomes?

A

4 non sister chromatids (2 X) attached to each other. Two chromosomes that have the same sequence of genes.

19
Q

When do the sister chromatids separate from each other?

A

Anaphase 2

20
Q

At what stage of meiosis does DNA replication take place?

A

Doesnt happen in mitosis/meiosis. Happens in S phase (interphase)

21
Q

Why the offspring of sexually-reproducing animals are genetically different from their parents?

A

Because of crossing over and independent assortment and they get half the genetic information from each parent so it not going to be exactly the same as one parent.

22
Q

What is karyotyping

A

a test to examine chromosomes in a sample of cells. This test can help identify genetic problems as the cause of a disorder or disease.

23
Q

Why does the MPF activity decline at the end of mitosis?

A

Enzyme complex breaks it down **

24
Q

At which stage independent assortment of chromosomes occurs?

A

Metaphase 1

25
Q

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea
plants?

A

Traits are inherited in discrete units. One from each parent.

26
Q

What are the two laws of Mendelian genetics?

A

Principles of segregation, which has become known as Mendel’s First Law: the first of Mendel’s laws states that genes are transferred as separate and distinct units from one generation to the next.

Principles of independent assortment, also known as Mendel’s Second Law: the law of independent assortment, is that the alleles of a gene pair located on one pair of chromosomes are inherited independently of the alleles of a gene pair located on another chromosome pair and that the sex cells containing various assortments of these genes fuse at random with the sex cells produced by the other parent

27
Q

What is Punnett square? How is it used?

A

A tool that helps to show all possible allelic combinations of gametes in a cross of parents with known genotypes in order to predict the probability of their offspring possessing certain sets of alleles.

https://www.youtube.com/watch?v=agQpPPQ5IVQ

28
Q

What is base-pairing?

A

A base pair consists of two complementary DNA nucleotide bases that pair together. One Purine (A,G)and one pyrimidine(T, C).

29
Q

Which enzyme break hydrogen bonds between complementary base pairs during DNA replication?

A

Helicase

30
Q

Which enzyme joins DNA fragments during DNA replication?

A

DNA polymerase

31
Q

What is semiconservative DNA replication?

A

one of the two original
strands is conserved in each daughter molecule

32
Q

How is the energy requirement of DNA replication met?

A

From the phosphate groups. triphosphate nucleotide attached to 3’ (phosphodiester bond) and PPi (2 phosphate) gets released as energy (H2O also gets released).

33
Q

What is euchromatin?

A

chromosome material which does not stain strongly except during cell division. It represents the major genes and is involved in transcription. They are more loosly packed and more expressed than heterochromatins

34
Q

Which enzyme removes supercoils that are generated during DNA replication?

A

Topoisomerase

35
Q

What is the chemical direction of DNA polymerization?

A

5 prime carbon to 3 prime carbon (5’ → 3’)

36
Q

What is the sequence of main steps of DNA replication?

A

the opening of the double helix and separation of the DNA strands, the priming of the template strand, through lagging and leading strands and the assembly of the new DNA segment.
_____________________________
1)Helicase will come in and break hydrogen bonds​
2)SSBPs will attach to the strands to prevent the double helix from reforming​
3)Primase will bind to the helix, which primes DNA polymerase by adding short RNA sequence ​
4)DNA polymerase will then start the replication process and add deoxyribonucleotides making a copy of the DNA​

37
Q

What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?

A

Prokaryotic chromosomes have a single origin of replication, while eukaryotic chromosomes have multiple origins of replication.

38
Q

When do centrioles duplicate during interface?

A

S phase

39
Q

What are Okazaki fragments?

A

During DNA replication, DNA is seperated and there would be a side going from 5’ to 3’ and a side going from 3’ to 5’. For the side going 5’ to 3’, the replication DNA would have to go 3’ to 5’, and replication can only occur from 5’ to 3’, so the DNA starts off at a further end and works backwards (5’ to 3’) making small fragments called Okazaki fragments.

40
Q

What is telomerase?

A

During DNA synthesis, No primer for DNA
polymerase near the end, so unreplicated end will degrade, shortening chromosome. Telomerase prevents the lagging strand from getting shorter with each replication by adding more
repeating bases to the end of the
lagging strand, catalyzing the
synthesis of DNA from an RNA
template carried with it.

41
Q

What causes xeroderma pigmentosum?

A

XP patients are unable to repair UV radiation-induced DNA damage due to
mutations in the nucleotide excision repair pathway.

Biology 1 Exam 3 (2 decks)

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