4.1 DNA, Genes And Chromosomes

Question 1

What is a gene?

Answer 1

A sequences of bases that codes for a specific polypeptide and functional RNA

Question 2

How many genes are there per one polypeptide?

Answer 2

1

Question 3

What are the 2 functional RNA?

Answer 3

tRNA
rRNA

Question 4

What is a locus?

Answer 4

The position in which the gene if found in DNA

Question 5

What does a sequence of bases in DNA determine?

Answer 5

A sequence of amino acids in a polypeptide

Question 6

What does homozygous mean?

Answer 6

Alleles are the same

Question 7

What does heterozygous mean?

Answer 7

Alleles are different

Question 8

How many alleles are there per gene?

Answer 8

2

Question 9

What is an allele?

Answer 9

Various forms of a gene

Question 10

Which type of cell DNA is found in mitochondria and chloroplasts?

Answer 10

Prokaryotic

Question 11

What is the difference in shape of the two cell types DNA?

Answer 11

Pro = circular (loop)
Euk = linear (two ends)

Question 12

In which type of cell is DNA shorter?

Answer 12

Prokaryotic

Question 13

Which type of cell DNA has introns?

Answer 13

Eukaryotic

Question 14

What are introns?

Answer 14

The non-coding regions of DNA
Tends to be two bases that repeat itself

Question 15

What are Exons?

Answer 15

Coding regions of DNA

Question 16

When are chromosomes visible?

Answer 16

When the cell is dividing

Question 17

How is DNA packed into a chromosome?

Answer 17

DNA wraps around his tone proteins to form a nucleosome
This coils to form super coils which makes up the chromatids

Question 18

How many chromosomes are present in a human cell?

Answer 18

46 chromosomes

Question 19

What is a homologous pair?

Answer 19

2 chromosomes with the same genes in the same loci

Question 20

What is bivalent?

Answer 20

A replicated homologous pair of chromosomes

Question 21

What is a karyotype?

Answer 21

The number and type of chromosomes in a cell

Question 22

What does haploid mean?

Answer 22

1 set of chromosomes - no homologous pairs

Question 23

What does diploid mean?

Answer 23

2 sets of chromosomes

Question 24

What is the genetic code?

Answer 24

The sequence of bases in DNA

Question 25

How many genetic codes do no code for an amino acid?

Answer 25

3

Question 26

How many bases code for 1 amino acid?

Answer 26

3

Question 27

What are the 3 features of the genetic code?

Answer 27

It is a degenerate code Non-overlapping Universal

Question 28

What does degenerate code mean?

Answer 28

more than 1 codon codes for a single amino acid

Question 29

What does non-overlapping mean?

Answer 29

Each base is only read once in each triplet

Question 30

What does universal genetic code mean?

Answer 30

Each triplet code codes for the same amino acid in any organism

Question 31

What amino acid is at the start of every polypeptide chain?

Answer 31

Methionine

Question 32

What is a genome?

Answer 32

The complete set of genes in cell or organism

Question 33

What is a proteome.

Answer 33

The entire set of proteins that can be produced by the genome

Question 34

What are 3 consecutive bases called in DNA?

Answer 34

A triplet

Question 35

What are 3 consecutive bases called in mRNA?

Answer 35

Codon

Question 36

What are 3 consecutive bases called in tRNA?

Answer 36

Anticodon

Question 37

What is the role of mRNA?

Answer 37

Carries the genetic code from DNA to the cytoplasm for protein synthesis

Question 38

What is the shape of mRNA?

Answer 38

A relatively long polynucleotide

Question 39

How is mRNA formed from DNA?

Answer 39

1. DNA strands separate by breaking H bonds 2. one of the strands is used as a template 3. complementary base pairs form 4. nucleotides joined by RNA polymerase 5. pre-mRNA is formed 6. splicing to remove introns to form mRNA

Question 40

What does the sequence of codons determine in mRNA?

Answer 40

The sequence of amino acids brought to the ribosome by tRNA

Question 41

What is the function of rRNA?

Answer 41

Makes up the ribosomes made in the nucleolus

Question 42

What is tRNA structure and features?

Answer 42

Relatively small Single- stranded helix which is folded into a clover leaf shape Hydrogen bonds Amino acid attachment site with the anticodon unfolded

Question 43

How is the amount of genes in a gamete different to a human cell?

Answer 43

Gamete has half as many chromosomes

Question 44

What is the advantage of DNA being a stable molecule?

Answer 44

So it is relatively unchanged and can be passed down through generations as the same molecule

Question 45

What is the advantage of mRNA being broken down relatively quickly?

Answer 45

It is used to make proteins so it would be wasteful to produce proteins constantly The mRNA is broken down to be reused

Question 46

What protein is prokaryotic DNA associated with?

Answer 46

Histones

Question 47

Which sex chromosome looks straight?

Answer 47

X

Question 48

What is the sex chromosome make up for a male?

Answer 48

XY

Question 49

What is the sex chromosome make up for a female?

Answer 49

XX

Question 50

What are the two threads in the chromosome called?

Answer 50

Chromatids

Question 51

What forms the non-coding parts of the gene?

Answer 51

By several short sequences that are usually two bases that repeat themselves

Question 52

What is the function of a STOP codon?

Answer 52

Signals a halt to protein synthesis in the cell

Question 53

What is the centre of a chromosome called?

Answer 53

Centromere

Question 54

How do you separate strands of DNA?

Answer 54

DNA helicase  Breaks hydrogen bonds between base pairs/ AT and GC/complementary bases 

Question 55

What is the role of single-stranded DNA fragments?

Answer 55

act as a template and determines the order of nucleotides

Question 56

What is the role of DNA nucleotides?

Answer 56

forms complementary pairs