B1 Gene Expression and Proteins Flashcards

1
Q

What is the structure of DNA?

A

Double helix 4 bases (adenine, thymine, guanine cytosine) Phosphate- (pentose)Sugar backbone Bases form ‘rungs’ of ladder

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2
Q

What is the central dogma of molecular biology?

A

DNA –> mRNA –> Protein

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3
Q

What are the purine bases found in nucleic acids?

A

Guanine and adenine

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4
Q

What are the pyrimidine bases in nucleic acids?

A

cytosine, thymine, uracil

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5
Q

What is chromatin structure?

A

DNA wrapped around histones (basic unit of chromatin = nucleosome)

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6
Q

What is a nucleosome?

A

The basic unit of chromatin

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7
Q

What does the nucleosome look like?

A

Beads on a string

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8
Q

What is the difference between euchromatin and heterochromatin?

A

Euchromatin - ‘unpacked’ beads on a stringHeterochromatin ‘packed’

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9
Q

When the chromatin fibre is supercoiled and associates with non-histone proteins, what is the structure called?

A

Chromosomal scaffold

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10
Q

What are the two copies of each chromosome called?

A

homologues

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11
Q

What is the centromere?

A

point of attachment to the mitotic spindleWhere chromatids are attached to each other in the chromosome.

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12
Q

What is a chromatid?

A

One copy of the duplicated chromosome

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13
Q

What is the telomere?

A

The endsof the chromosome.

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14
Q

What is the purpose of the telomeres?

A

To protect the chromosome during replication

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15
Q

What is a karyotype?

A

The stereotypic number and shape of chromosomes in a species during metaphase

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16
Q

What is the importance of the karyotype?

A

Analysis can be used to diagnose gross chromosomal abnormalities

17
Q

What happens during G0 phase?

A

Rest; the cell has not started to divide

18
Q

What happens during the G1 phase?

A

Cell starts making more proteins and growing larger

19
Q

What happens during the S phase?

A

DNA synthesis - chromosomes copied

20
Q

What happens during the G2 phase?

A

The cell checks the DNA and prepares for mitosis

21
Q

How long does mitosis last in the average body cell?

A

30 - 60 minutes

22
Q

How long does the G0 phase last?

A

Variable; once the signal to reproduce has been sent to the cell it moves into G1.

23
Q

How long does the G1 phase last?

A

18- 30 hours

24
Q

How long does the G2 phase last?

A

2-10 hours

25
Q

How long does the S phase last?

A

18-20 hours

26
Q

What is the order of the stages of mitosis?

A

ProphasePrometaphaseMetaphaseAnaphaseTelophaseCytokinesis

27
Q

What happens during prophase?

A

Chromosomes condenseCentrosomes migrateto opposite polesMitotic spindle starts forming

28
Q

What happens during prometaphase?

A

Nuclear envelope breaks downSpindle microtubules attach to chromosomesSpindle microtubules start pulling chromosomes

29
Q

What happens during metaphase?

A

Chromosomes are pulled to the equator of the cellChromosomes line up on the metaphase plate

30
Q

What happens during telophase?

A

Chromosomes reach opposite poles and decondenseVirtually opposite of prophase

31
Q

How do the spindle microtubules attach to the chromosomes?

A

Via the kinetochore

32
Q

How are the spindle poles formed?

A

Through the separation of the centrosomes

33
Q

What is the kinetochore?

A

Complex structure made of proteins that binds to specific centromeric DNA sequences.

34
Q

How can the mitotic spindle form around the chromosomes?

A

Centrosomes move away from each other, around nuclear envelopeSpindle forms with movement of centrosomes away from each otherNuclear envelope needs to disappear (break down)

35
Q

What happens during anaphase?

A

Sister chromatids separate and move to opposite polesWhere the chromosomes are actually pulled apart