DNA, genes, & the continuity of life (Unit 4, Topic 1)

Question 1

The basic building block of nucleic acids. Consists of a sugar molecule (DNA or RNA) attached to a phosphate group and a nitrogen-containing base.
Bases in DNA include adenine (A), cytosine (C), guanine (G), and thymine (T)
Bases in RNA include adenine (A), cytosine (C), guanine (G), and uracil (U).

Answer 1

Nucleotide bases

Question 2

The structural framework of nucleic acids, composed of alternating sugar and phosphate groups

Answer 2

Sugar-phosphate backbone

Question 3

A protein found in chromosomes. They bind to DNA, help give chromosomes their shape, and help control the activity of genes

Answer 3

Histones

Question 4

1. Begins with separation of double-stranded DNA via enzyme helicase at the replication origin
2. DNA polymerase adds complementary DNA to original DNA. primers are added by enzyme primase to single strands to allow elongation of new strands.
3. Leading strand and lagging strand are replicated, with RNA primers are added to open replication fork for synthesis. Creates Okazaki fragments.
4. RNA primers are removed and replaced with DNA. DNA ligase joins fragments together to form new DNA molecules.

Answer 4

DNA replication

Question 5

An enzyme that breaks down the hydrogen bonds holding two DNA strands together.

Answer 5

DNA helicase

Question 6

An enzyme that is responsible for assembling nucleotides to form new copies of DNA.

Answer 6

DNA polymerase

Question 7

An enzyme that facilitates the joining of DNA strands together

Answer 7

DNA ligase

Question 8

3’ to 5’ direction

DNA template from the middle of the replication bubble (point of origin) to the fork

Answer 8

Leading strand

Question 9

5’ to 3’ direction

DNA template from the fork to the middle of the replication bubble (point of origin)

Answer 9

Lagging strand

Question 10

Where a parent somatic cell divides into two genetically identical diploid daughter cells

Answer 10

Mitosis

Question 11

Where a parent germline cell divides into four genetically unique haploid cells

Answer 11

Meiosis

Question 12

Mitosis and meiosis

Answer 12

Cell replication (division)

Question 13

Centromere
Telomere
Homologous chromosomes
Sister chromatids

Answer 13

Chromosome structure

Question 14

The chromosomes condense, the nuclear envelope degrades, the centrioles begin to form spindle fibres, and the homologous chromosomes crossover to undergo recombination

Answer 14

Prophase I

Question 15

The spindle fibres attach to the centromere of the chromosomes and the HOMOLOGOUS chromosomes align randomly and independently in the metaphase plane of the cell

Answer 15

Metaphase I

Question 16

The spindle fibres contract, causing the homologous chromosomes to separate

Answer 16

Anaphase I

Question 17

The nuclear envelope reforms around the separated chromosomes, the spindle fibres are degraded, and the chromosomes de-condense

Answer 17

Telophase I & Telophase II

Question 18

The plasma membrane pinches in the centre of the cell, creating two daughter cells
Occurs between the first round and second round of stages as well as after the second round of stages at the end.

Answer 18

Cytokinesis

Question 19

The chromosomes re-condense, the nuclear envelope degrades, the centrioles begin to form spindle fibres

Answer 19

Prophase II

Question 20

The spindle fibres attach to the centromere of the chromosomes and the chromosomes align randomly and independently in the metaphase plane of the cell

Answer 20

Metaphase II

Question 21

The spindle fibres contract, causing the sister chromatids to separate

Answer 21

Anaphase II

Question 22

Recombination

Independent assortment

Answer 22

Processes occurring in meiosis

Question 23

Occurs in Prophase I

Describes the process in which homologous chromosomes ‘cross over’ at the point known as chiasma

Answer 23

Recombination

Question 24

Occurs in Metaphase II

Describes the process in which maternal and paternal homologous chromosomes align independently of one another

Answer 24

Independent assortment