Chapter 9

Question 1

What is a nucleosome

Answer 1

DNA strands wrapped around eight histone proteins

Question 2

What is a chromatin

Answer 2

A tangled network of DNA in the nucleus of a cell that is not dividing

Question 3

What is a gene

Answer 3

Section of a chromosome that contains the nucleotide sequence coding for a particular trait

Question 4

What is the difference between nuclear DNA and mitochondrial DNA

Answer 4

Nuclear - long strands, bound to histones
mtDNA - small, circular molecules not bound to proteins

Question 5

roughly how many molecules of mtDNA are found in each mitochondrion

Answer 5

5-10

Question 6

What is a genome

Answer 6

The complete set of genetic information in an organism

Question 7

How many genes are in mtDNA and what do they code for?

Answer 7

37 genes. 24 code for making transfer RNA. 13 code for making enzymes required for cellular respiration

Question 8

How does helicase work

Answer 8

It breaks the weak hydrogen bond between base pair to separate the double helix

Question 9

What is the role of DNA polymerase

Answer 9

Adds new nucleotides to the DNA strand

Question 10

What is the role of DNA ligase

Answer 10

Joins short sections of DNA together

Question 11

What is the role of messenger RNA

Answer 11

Takes genetic code into cytoplasm allowing genetic code to be read by ribosomes

Question 12

What is the role of ribosomal RNA

Answer 12

Ensures correct alignment of mRNA and tRNA and ribosome. Has an enzymatic role in formation of peptide bonds between amino acids

Question 13

What is the role of transfer RNA

Answer 13

carries a specific amino acid from the cytoplasm to the ribosome to add to a polypeptide chain

Question 14

Summarize what transcription is

Answer 14

Process by which genetic information is copied from DNA to the mRNA

Question 15

What triggers transcription

Answer 15

chemical messenger that enters the nucleus and binds to DNA at the relevant gene

Question 16

What are introns and exons

Answer 16

introns - sections of DNA that DO NOT code for protein
exons - sections of DNA that code for protein

Question 17

What is the template strand and the coding strand

Answer 17

template - strand that is copied
coding - strand same as the one in the mRNA molecule

Question 18

What is the promotor region

Answer 18

section on the DNA where the mRNA can attach to initiate transcription

Question 19

Summarize translation

Answer 19

the production of a protein with the information provided by the mRNA

Question 20

What is the start codon

Answer 20

AUG, methionine, the point at which the ribosome first attaches to begin protein synthesis

Question 21

What is an anticodon

Answer 21

sequence 3 bases in tRNA molecule that binds to complementary codon in an mRNA molecule, to specify a particular amino acid

Question 22

How much energy does the formation of one peptide bond require

Answer 22

Breakdown of one ATP molecule

Question 23

What is gene expression

Answer 23

process of copying information from DNA on to mRNA and then translating the message into a series of amino acids to form a protein

Question 24

What does a gene being ‘switched on’ or ‘switched off’ mean

Answer 24

Genes that are making mRNA are switched on. Not making mRNA means they’re switched off

Question 25

What determines whether a gene is switched on or off

Answer 25

age of cell, environment, type of cell, time of day, signaling from other cells

Question 26

write the steps of protein synthesis (refer page 256)

Question 27

How are lipids and carbohydrates synthesized

Answer 27

by enzymes, which are proteins made from protein synthesis

Question 28

What is epigenetics

Answer 28

Altering expression of a gene without changing the gene structure. Can occur due to environmental factors

Question 29

What is acetylation

Answer 29

The addition of an acetyl group to a histone protein. Attraction between histones and DNA weakens, relaxing the chromatin structure. Promotes transcription by allowing polymerase access

Question 30

What is methylation

Answer 30

Addition of a methyl group to histone protein or DNA molecule. Occurs at sites where a cytosine is adjacent to guanine. Known as CpG sites, cytosine phosphorous–guanine. Inhibits gene expression by tightening molecule and restricting access to RNA polymerase. However, depending on where methyl group attaches and how many, it may increase or decrease transcription

Question 31

What is the difference between a gene and a chromosome

Answer 31

A gene is a segment of DNA that codes for making a protein and a chromosome is coiled up DNA

Question 32

describe the process of DNA replication (occurs during S phase) this is a semi-conservative process

Answer 32

Double helix un-winded by DNA helicase, weak hydrogen bonds broken between nucleotides. DNA polymerase works in 5' to 3' direction so nucleotides are assembled in continuous fashion on one end and short fragments on the other. These fragments are joined by DNA ligase. Each of the two new molecules with one OG strand and one new strand wind into a double helix