B1 Gene Expression and Proteins

Question 1

What is the structure of DNA?

Answer 1

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

Question 2

What is the central dogma of molecular biology?

Answer 2

DNA –> mRNA –> Protein

Question 3

What are the purine bases found in nucleic acids?

Answer 3

Guanine and adenine

Question 4

What are the pyrimidine bases in nucleic acids?

Answer 4

cytosine, thymine, uracil

Question 5

What is chromatin structure?

Answer 5

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

Question 6

What is a nucleosome?

Answer 6

The basic unit of chromatin

Question 7

What does the nucleosome look like?

Answer 7

Beads on a string

Question 8

What is the difference between euchromatin and heterochromatin?

Answer 8

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

Question 9

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

Answer 9

Chromosomal scaffold

Question 10

What are the two copies of each chromosome called?

Answer 10

homologues

Question 11

What is the centromere?

Answer 11

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

Question 12

What is a chromatid?

Answer 12

One copy of the duplicated chromosome

Question 13

What is the telomere?

Answer 13

The endsof the chromosome.

Question 14

What is the purpose of the telomeres?

Answer 14

To protect the chromosome during replication

Question 15

What is a karyotype?

Answer 15

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

Question 16

What is the importance of the karyotype?

Answer 16

Analysis can be used to diagnose gross chromosomal abnormalities

Question 17

What happens during G0 phase?

Answer 17

Rest; the cell has not started to divide

Question 18

What happens during the G1 phase?

Answer 18

Cell starts making more proteins and growing larger

Question 19

What happens during the S phase?

Answer 19

DNA synthesis - chromosomes copied

Question 20

What happens during the G2 phase?

Answer 20

The cell checks the DNA and prepares for mitosis

Question 21

How long does mitosis last in the average body cell?

Answer 21

30 - 60 minutes

Question 22

How long does the G0 phase last?

Answer 22

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

Question 23

How long does the G1 phase last?

Answer 23

18- 30 hours

Question 24

How long does the G2 phase last?

Answer 24

2-10 hours

Question 25

How long does the S phase last?

Answer 25

18-20 hours

Question 26

What is the order of the stages of mitosis?

Answer 26

ProphasePrometaphaseMetaphaseAnaphaseTelophaseCytokinesis

Question 27

What happens during prophase?

Answer 27

Chromosomes condenseCentrosomes migrate to opposite polesMitotic spindle starts forming

Question 28

What happens during prometaphase?

Answer 28

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

Question 29

What happens during metaphase?

Answer 29

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

Question 30

What happens during telophase?

Answer 30

Chromosomes reach opposite poles and decondenseVirtually opposite of prophase

Question 31

How do the spindle microtubules attach to the chromosomes?

Answer 31

Via the kinetochore

Question 32

How are the spindle poles formed?

Answer 32

Through the separation of the centrosomes

Question 33

What is the kinetochore?

Answer 33

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

Question 34

How can the mitotic spindle form around the chromosomes?

Answer 34

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

Question 35

What happens during anaphase?

Answer 35

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