Week 4

Question 1

Making a mRNA copy of a gene is known as what?

Answer 1

Transcription

Question 2

What a the 3 main parts of a gene?

Answer 2

Promoter, Coding sequence and the terminator.

Question 3

The process of producing a protein from mRNA is known as what?

Answer 3

Translation

Question 4

Which strand of DNA is used to make mRNA?

Answer 4

The template strand

Question 5

Before mRNA can be translated into proteins, what must happen?

Answer 5

It must be processed, i.e.Introns must be removed by splicing.

Question 6

What is a codon?

Answer 6

A sequence of 3 base pairs that codes for an amino acid.

Question 7

What is meant by the genetic code?

Answer 7

The 4 letter code of DNA can represent 20 different amino acids by different combinations in a codon, i.e. there are 64 possible combinations.

Question 8

Codons in mRNA are recognised by anticodons on what molecule?

Answer 8

tRNA.

Question 9

What are the 3 steps in translation?

Answer 9

Initiation, elongation, termination.

Question 10

What are the phases of the cell cycle?

Answer 10

Growth 1 (G1), Syntheses (S), Growth 2 (G2), Mitosis (M).

Question 11

During which phase is DNA replicated?

Answer 11

The S phase.

Question 12

During which phase are organelles duplicated?

Answer 12

G1 phase.

Question 13

What is meant by semi-conservative replication?

Answer 13

Each new double stranded DNA contains half of the old strand of DNA.

Question 14

What are the stages of mitosis?

Answer 14

Prophase, metaphase. anaphase. and telephase.

Question 15

The nuclear envelope disappears in what stage?

Answer 15

Prophase

Question 16

During anaphase the 2 sister chromatids are pulled apart by attaching to what?

Answer 16

Microtubules of the mitotic spindle.

Question 17

What are the 3 fates of a cell?

Answer 17

1. To remain alive and functioning without dividing.
2. To grow and divide.
3. To die.

Question 18

What is the importance of checkpoints in the cell cycle.

Answer 18

To halt division if conditions are not right, e.g. if the DNA hasn’t been copied properly or there are not enough nutrients.

Question 19

What is the difference between apoptosis and necrosis?

Answer 19

Apoptosis is programmed cell death and doesn’t disrupt surrounding cells, necrosis is uncontrolled cell death that harms surrounding cells due to spillage of cell contents.

Question 20

How many chromosome pairs do humans have?

Answer 20

23

Question 21

A variant of a gene is known as what?

Answer 21

An allele

Question 22

When an individual has 2 identical alleles of the same gene they are said to be what?

Answer 22

Homozygous.

Question 23

What does it mean when a cell is duploid or haploid?

Answer 23

Duploid means 2 copies of each chromosome, haploid means only one copy.

Question 24

What is a trait?

Answer 24

An observable feature of an organism, e.g. eye colour.

Question 25

What is meant be a dominant trait?

Answer 25

Only one copy of the gene is needed for the trait to appear.

Question 26

What is the difference between phenotype and genotype.

Answer 26

A phenotype is the observable end-product of genes, i.e. a trait, while a genotype is the genetic sequence itself.

Question 27

If parents are heterozygous for a certain gene, i.e. they both have a dominant B gene and a recessive b gene, what is the probability of a child being homozygous for the recessive trait?

Answer 27

25%

Question 28

What is meant by a homologous gene or chromosome?

Answer 28

They code for the same proteins, even though there may be variance in the exact sequence.

Question 29

What is the law of segregation?

Answer 29

Genes pairs are transferred to gametes with equal probability.

Question 30

What is the law of independent assortment?

Answer 30

Each gene is transferred to a gamete independently of others, i.e. the probability of gene A being transferred to the gamete does not affect the probability of the B gene being transferred, as long as they’re on different chromosomes.

Question 31

What can we use to trace a trait from a family history?

Answer 31

A pedigree chart.

Question 32

Describe the process of DNA replication.

Answer 32

Stage 1: Initiation 1. Two complementary strands are separated by special enzymes (helical) 2. DNA strands are untwisted and separated Stage 2: 1. DNA polymerase attaches the correct bases to the complement template strand 2. DNA polymerase contuniues to attach nucleotides to the template stands Stage 3: Termination 1. Once both strands are finished the DNA is ‘proof read’ by enzymes to eliminate errors

Question 33

What is a gene?

Answer 33

Functional segment of DNA that provides genetic information to construct a particular protein

Question 34

What occurs during transcription in protein synthesis?

Answer 34

1.Initiation: promoter region initiates the start of transcription 2.elongation: RNA polymerase unwinds DNA segment and aligns correct nucleic acid with its complementary base 3.termination: when polymerase reaches end of gene the stop signal triggers the enzyme to terminate transcritption and release the mRNA transcript.

Question 35

What occurs during the process of translation in protein synthesis?

Answer 35

1.Initiation - mRNA transcript binds to ribosome complex 2. Elongation - tRNA anticodon bonds with the corresponding codon on the mRNA and its amino acid joins the growing polypeptide chain 3. Termination - process stops when codon with stop message is reached signalling and releasing newly transcribed protein.