B1 Gene Expression and Proteins Flashcards Preview

Phase I Medicine > B1 Gene Expression and Proteins > Flashcards

Flashcards in B1 Gene Expression and Proteins Deck (35):
1

What is the structure of DNA?

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

2

What is the central dogma of molecular biology?

DNA --> mRNA --> Protein

3

What are the purine bases found in nucleic acids?

Guanine and adenine

4

What are the pyrimidine bases in nucleic acids?

cytosine, thymine, uracil

5

What is chromatin structure?

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

6

What is a nucleosome?

The basic unit of chromatin

7

What does the nucleosome look like?

Beads on a string

8

What is the difference between euchromatin and heterochromatin?

Euchromatin - 'unpacked' beads on a stringHeterochromatin 'packed'

9

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

Chromosomal scaffold

10

What are the two copies of each chromosome called?

homologues

11

What is the centromere?

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

12

What is a chromatid?

One copy of the duplicated chromosome

13

What is the telomere?

The ends of the chromosome.

14

What is the purpose of the telomeres?

To protect the chromosome during replication

15

What is a karyotype?

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

16

What is the importance of the karyotype?

Analysis can be used to diagnose gross chromosomal abnormalities

17

What happens during G0 phase?

Rest; the cell has not started to divide

18

What happens during the G1 phase?

Cell starts making more proteins and growing larger

19

What happens during the S phase?

DNA synthesis - chromosomes copied

20

What happens during the G2 phase?

The cell checks the DNA and prepares for mitosis

21

How long does mitosis last in the average body cell?

30 - 60 minutes

22

How long does the G0 phase last?

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

23

How long does the G1 phase last?

18- 30 hours

24

How long does the G2 phase last?

2-10 hours

25

How long does the S phase last?

18-20 hours

26

What is the order of the stages of mitosis?

ProphasePrometaphaseMetaphaseAnaphaseTelophaseCytokinesis

27

What happens during prophase?

Chromosomes condenseCentrosomes migrate to opposite polesMitotic spindle starts forming

28

What happens during prometaphase?

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

29

What happens during metaphase?

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

30

What happens during telophase?

Chromosomes reach opposite poles and decondenseVirtually opposite of prophase

31

How do the spindle microtubules attach to the chromosomes?

Via the kinetochore

32

How are the spindle poles formed?

Through the separation of the centrosomes

33

What is the kinetochore?

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

34

How can the mitotic spindle form around the chromosomes?

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

What happens during anaphase?

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