3.2

Question 1

Why is prokaryotic DNA referred to as Naked DNA

Answer 1

because it is not organized around associated histone proteins

Question 2

Why are plasmids useful

Answer 2

they are much smaller circular DNA molecules that are easily exchanges between prokaryotes and may contain several genes

Question 3

What can be said abut plasmid functions

Answer 3

It contains several genes related to one specific function like antibiotic resistance.

Question 4

What is DNA wrapped around in eukaryotes

Answer 4

wrapped around globular histones

Question 5

what does it mean if a molecule is basic

Answer 5

alkaline

Question 6

what is a histone

Answer 6

a basic alkaline protein

Question 7

What forms is DNA organized in during interphase

Answer 7

chromatin making it harder to see

Question 8

Why is having DNA in chromatin useful

Answer 8

allows ~DNA transcribing enzymes to access the genes with the information they need to keep the cell functioning

Question 9

What happens to the chromosomes in the first stages of mitosis and meiosis

Answer 9

the chromosomes condense to form highly organized X shaped structures visible with a light microscope

Question 10

What are sister chromatids

Answer 10

identical copies of the chromosomes

Question 11

What is the place where the two sister chromatid strands connect

Answer 11

the centromere

Question 12

What does the supercoiled state of DNA allow for

Answer 12

the DNA to be separated without being tangled and torn

Question 13

What are homologous chromosomes

Answer 13

they carry the same set of the genes in the same locations but there can be small differences between the nucleotide sequences of the same gene

Question 14

What are different versions of the same gene called

Answer 14

alleles

Question 15

How do alleles differ from each other

Answer 15

usually by only a f ew DNA base pairs

Question 16

How many pairs of chromosomes is the human genome arranges into

Answer 16

23 pairs of chromosomes, 46 in total

Question 17

what are sex chromosomes

Answer 17

one pair they determine the sex of the organism

Question 18

What are the remaining 22 pairs of chromosomes called

Answer 18

autosomes

Question 19

what are autosomes

Answer 19

chromosomes that do not influence sex determination

Question 20

Compare the genome size of humans to a virus that infects bacteria

Answer 20

Humans have a genome around 3200 million base pairs whereas T2 phage have around 0.18 million base pairs

Question 21

Compare the genome size of humans to E.coli

Answer 21

Humans have a genome around 3200 million base pairs whereas E.coli have around 5 million base pairs

Question 22

Compare the genome size of humans to a fruit fly

Answer 22

Humans have a genome around 3200 million base pairs whereas fruit fly would have 140 million base pairs

Question 23

Compare the genome size of humans to a Woodland plant

Answer 23

Humans have a genome around 3200 million base pairs whereas woodland plants have around 150 000 million base pairs

Question 24

What do haploid sperm and haploid egg fuse to form

Answer 24

a zygotę

Question 25

What do diploid nuclei have

Answer 25

pairs of homologous chromosomes

Question 26

What are chromosomes in a homologous pair referred to

Answer 26

a homologue

Question 27

What is a structure of two homologous called

Answer 27

a tetrad

Question 28

You should be able to compare the diploid chromosome numbers of Homo sapiens , Pan troglodytes , Canis familiaris , Oryza sativa , and Parascaris equorum .

Answer 28

Parascaris equorum (equine roundworm) 4 Oryza sativa (rice plant) 24 Homo sapiens (human) 46 Pan troglodytes (chimpanzee) 48 Cani s familiaris (domestic dog) 78

Question 29

What does a haploid nuclei posses

Answer 29

one chromosomes of each pair of homologs chromosomes

Question 30

What does a karyogran show

Answer 30

the chromosomes of an organism in homologs pairs of decreasing length

Question 31

What is a karyotype

Answer 31

a property of a cell, the number and type of chromosomes present in the nucleus.

Question 32

What can a karyogram be used for

Answer 32

to deduce the sex of an individual to find missing or extra chromosomes and to detect other chromosomal mutations

Question 33

When does down syndrome occur

Answer 33

when there are three copies of chromosome 21 present

Question 34

When does non-disjunction occur

Answer 34

when there are three chromosomes for 21, indicating that non disjunction has occurred

Question 35

What is autoradiography

Answer 35

a technique that uses X ray film to visualize the two dimensional distribution of a radioactivey labelled substance

Question 36

Who published autoradiography

Answer 36

John Cairns

Question 37

What does Autoradiography do

Answer 37

measures the length of DNA molecules

Question 38

What did Cairns do

Answer 38

he produced images fo DNA molecules from Coli through autoradiography

Question 39

What method did Cairns follow

Answer 39

He produced thymidine labelled with radioactive hydrogen then he grew coli bacteria in a medium containing the radioactive thymidine then the e.coli cells replicated their DNA, they used the radioactive thymine to create radioactive DNA he then lysed the cells to release the cell contents, including the intact bacterial DNA onto slides Next, he covered the slides with photographic emulsion and stored them in the dark fro two months during that period, high energy electrons emitted by the radioactive deca of 3H within the DNA caused the appearance of dark sports on the photographic emulsion. the length of the DNA could then be measured.

Question 40

What creates the dark spots seen on the photographic emulsion in an autoradiograph?

Answer 40

high energy electrons released from the DNA itself

Question 41

Cairns used autoradiography as a technique to measure the length of:

Answer 41

DNA molecules

Question 42

What are the features of bacterial genetic material?

Answer 42

Bacterial genetic material is not associated with proteins, and consists of a DNA loop with a single copy of each gene.

Question 43

How many daughter cells are produced in meiosis

Answer 43

4

Question 44

What techniques was used by Cairns to measure the length of a DNA molecule?

Answer 44

autoradiography technique with radioactive isotopes

Question 45

What name is given to the exact position of a gene on a chromosome?

Answer 45

locus