Unit 4 Topic 1 - DNA

Question 1

What 3 components make up a nucleotide?

Answer 1

A phosphate, a sugar and a nitrogen base

Question 2

What number carbon is the P group attached to?

Answer 2

5th carbon

Question 3

What are the complementary base pairs?

Answer 3

Adenine - Thymine
Guanine - Cytosine

Question 4

Explain the composition of chromosomes

Answer 4

Consists of DNA strands coiled around histone proteins to create a supercoil

Question 5

What are the stages of Mitosis

Answer 5

prophase, metaphase, anaphase, telophase, cytokinesis

Question 6

List and explain the three steps of DNA replication.

Answer 6

1. The enzyme helicase ‘unzips’ the DNA to create a fork
2. the enzyme DNA polymerase adds nucleotides to the template strands to built two new complementary strands.
3. two identical DNA helices are produced

Question 7

Explain the difference between sister chromatids and homologous chromosomes

Answer 7

Sister chromatids refer to each half of a chromosome, whereas homologous chromosomes refer to an inherited pair of chromosomes

Question 8

What are the phases of meiosis?

Answer 8

Interphase, prophase, metaphase, anaphase, telophase, cytokinesis

Question 9

How many chromosomes do each haploid cell have after meiosis?

Answer 9

23

Question 10

What is spermatogenesis?

Answer 10

the production of sperm in the testes

Question 11

how many haploid sperm cells are produced after meiosis

Answer 11

4

Question 12

What is Oogenesis

Answer 12

The production of ovaries in females

Question 13

How many viable haploid cells are produced in Oogenesis

Answer 13

1, The other three become polar bodies

Question 14

When do the stages of Oogenesis occur in women?

Answer 14

Mitosis -> before birth
Meiosis 1 -> at puberty
Meiosis 2 -> at pregnancy

Question 15

Identify the key differences between spermatogenesis and oogenesis

Answer 15

Spermatogenesis produced 4 viable haploid cells, Oogenesis only produces 1.

Spermatogenesis is a constant process that begins at puberty, whereas Oogenesis is a discontinuous process.

Question 16

What is independent assortment

Answer 16

the orientation of chromosomes during metaphase is random, contributing to genetic variation

Question 17

what is random feralization

Answer 17

The random chance of any sperm and egg fertilizing, resulting in random variation

Question 18

What is a gene

Answer 18

a sequence of nucleotides that code for a gene product

Question 19

What is a genome

Answer 19

the complete set of genetic material in an organism

Question 20

What makes up a codon

Answer 20

3 nucleotides

Question 21

What is a gene’s coding region called

Answer 21

exon

Question 22

what is a gene’s non-coding region called.

Answer 22

intron

note: It is unclear what the exact purpose of these regions is but they may aid in gene regulation

Question 23

List the 4 features of a gene’s structure

Answer 23

start and stop codons
promoter region
exon
intron

Question 24

What is the code for a start codon

Answer 24

ATG (which becomes AUG, codes for methionine)

Question 25

What is a promoter region

Answer 25

A TATAAA sequence where the RNA polymerase binds to start transcription.

Question 26

What is an exons role?

Answer 26

they are used to make RNA or proteins

Question 27

Define transcription

Answer 27

the synthesis of mRNA from DNA

Question 28

List and define the 3 steps of transcription

Answer 28

Initiation - RNA polymerase binds to the promoter region and breaks the hydrogen bonds causing DNA strands to separate Elongation - RNA polymerase moves along the gene creating an RNA strand from complementary nucleotides Termination - RNA polymerase reaches the stop codon which causes the RNA to detach

Question 29

What is translation

Answer 29

The process in which mRNA is read and used to build a chain of amino acids (polypeptide chain)

Question 30

What is the role of transfer RNA (tRNA)

Answer 30

tRNA adds the specific amino acid to the polypeptide chain

Question 31

Thymine is replaced with what base in RNA?

Answer 31

Uracil

Question 32

List and define the stages of translation

Answer 32

Initiation - Ribosome assembles around mRNA and the first tRNA is put in place. Elongation - mRNA is read and amino acids are added into the polypeptide chain Termination - finished protein chain is released

Question 33

What is the purpose of gene expression

Answer 33

To produce a functional gene product

Question 34

What is a transcription factor

Answer 34

Proteins that control gene expression

Question 35

What are epigenetics

Answer 35

environmental mechanisms that alter gene expression without directly involving the DNA sequence (mechanisms can include diet or pollutants)

Question 36

Explain the difference between incomplete dominance and codominance

Answer 36

Incomplete dominance results in a blended phenotype (e.g. a red and white flower may produce a pink flower) Codominance results in both parents phenotypes being represented

Question 37

What is a Polymerase Chain Reaction

Answer 37

The replication of a single or few copies of DNA into millions or billions of copies so that the DNA can be amplified and studied