Topic 2:3 DNA structure

Question 1

quickly state the function of DNA

Answer 1

DNA stores and transmits genetic information; it functions in the same way in all living things.

Question 2

DNA contains the instructions for…

Answer 2

constructing other components of a cell, such a proteins and RNA molecules

Question 3

describe the structure of DNA in eukaryotes

Answer 3

DNA molecules are wound tightly around globular proteins called histones, forming a DNA-protein mixture called chromatin.

Question 4

what are the four nitrogenous bases?

Answer 4

Adenine, Thymine, Guanine and Cytosine

Question 5

What are A, T, C and G

Answer 5

nitrogenous bases

Question 6

the bonding between the strands/nitrogenous bases is….

Answer 6

complementary. Adenine always pairs with Thymine, Cytosine always pairs with Guanine.

Question 7

the two strands are bonded together by…. (and why?)

Answer 7

weak hydrogen bonds. so they can separate and reform easily when DNA is replicated.

Question 8

what model describes the shape of DNA

Answer 8

double helix

Question 9

DNA has direction referred to as…

Answer 9

3’ prime and 5’ prime. Complementary strands run in opposite directions.

Question 10

chromatin is organised into structures called

Answer 10

chromosomes (linear)

Question 11

what is DNA composed of?

Answer 11

DNA is composed of nucleotides that form the repeating unit of each strand.

Question 12

what do nucleotides consist of?

Answer 12

Nucleotides consist of a sugar molecule, deoxyribose, a phosphate group and a nitrogenous base.

Question 13

what is a karyogram?

Answer 13

When the chromosomes are condensed and visible a photograph can be taken. The chromosomes in the photo can be cut out, arranged in order of size, numbered and pasted to produce a composite photo called a karyogram (shows a karyotype).

Question 14

how do male and female karyotypes differ?

Answer 14

Male and female karyotypes vary only by one pair of chromosomes XX for females and XY for males.

Question 15

genes are located…

Answer 15

in specific positions on specific chromosomes called the gene’s locus or gene loci.

Question 16

A chromosome can be identified by…

Answer 16

its genes or a particular gene locus. They vary in:
-Genes present
-Size and shape
-Banding pattern

Question 17

what’s a gene?

Answer 17

A segment of the DNA molecule that codes for a protein molecule, a polypeptide or an RNA molecule

Question 18

what do genes do?

Answer 18

determine what proteins are made within a cell which in turn determines the structure and function of the cell.

Question 19

prokaryotic or eukaryotic: chromosomes are found in a part of the cytoplasm called the nucleoid.

Answer 19

prokaryotic

Question 20

prokaryotic or eukaryotic: Single circular chromosome plus plasmids. Simple genome.

Answer 20

prokaryotic. (also could be found in mitochondria and chloroplasts)

Question 21

prokaryotic or eukaryotic:
chromosomes contain only one copy of each gene

Answer 21

Prokaryotic.

Question 22

prokaryotic or eukaryotic: chromosomes don’t have homologous pairs

Answer 22

prokaryotic

Question 23

prokaryotic or eukaryotic: chromosomes are made of chromatin (DNA wrapped around histone proteins)

Answer 23

eukaryotic

Question 24

prokaryotic or eukaryotic: Chromosomes are organized into homologous pairs and observed as a karyotype.

Answer 24

eukaryotic

Question 25

prokaryotic or eukaryotic: Copies chromosomes, then the cells grows, then goes through mitosis to organise chromosomes into two equal groups.

Answer 25

eukaryotic.

Question 26

prokaryotic or eukaryotic: Copies its chromosome and divides immediately afterwards.

Answer 26

prokaryotic