Topic 3.2: Chromosomes

Question 1

Prokaryotes chromosomes

Answer 1

a) Have a single circular molecule made of naked DNA (Genophore)
b) May have additional plasmids

Question 2

Eukaryotes chromosomes

Answer 2

a) Multiple linear DNA molecules packaged with histones

b) Do not have plasmids

Question 3

Plasmids

Answer 3

Small, autonomous circular DNA molecules

Question 4

Centromere

Answer 4

Constriction point of a chromosome

a) p-arm (short)
b) q-arm (long)

Question 5

Identifying the region in which a gene is positioned

Answer 5

a) Chromosome
b) Arm
c) G band location

Question 6

Homologous Chromosomes

Answer 6

Paired chromosomes inherited from both parents in sexually reproducing animals

Question 7

Characteristics of Homologous Chromosomes

Answer 7

a) Structural features

b) Genes at the same loci positions

Question 8

Diploid

Answer 8

a) Two sets of chromosomes

b) Somatic cells in the organism

Question 9

Haploid

Answer 9

a) One set of chromosomes

b) Sex cells / Gametes

Question 10

Number of chromosomes in humans

Answer 10

23 pairs of chromosomes

Question 11

Homologous Autosomes

Answer 11

a) 22 pairs

b) Do not determine sex

Question 12

Sex chromosomes

Answer 12

a) 23rd pair

b) XX / XY

Question 13

Y Chromosome

Answer 13

Contains the genes for developing male sex characteristics (SRY gene)

Question 14

Karyotype

Answer 14

Identify the number and types of chromosomes in a eukaryotic cell

Question 15

Functions of karyotyping

Answer 15

a) Identify the sex of offspring

b) Diagnose potential chromosome abnormalities

Question 16

Processo of karyotyping

Answer 16

a) Harvesting cells
b) Chemically inducing cell division, arresting mitosis while the chromosomes are condensed
c) Determine whether chromosomes appear with sister chromatids or not

Question 17

Karyogram

Answer 17

Visual profile that shows the chromosomes of a

cell in homologous pairs of decreasing length

Question 18

Autoradiography (John Cairns)

Answer 18

Technique for measuring the length of DNA molecules while uncoiled

Question 19

Process of Autoradiography

Answer 19

a) Radioactive thymidine is incorporated into a cell’s DNA
b) Chromosomes were fixed to a photographic surface and treated with silver bromide (AgBr)
c) Radiation converts silver ions into insoluble grains that is visible via electron microscopy when a film is developed

Question 20

Chromosome number and species

Answer 20

Chromosome number is a characteristic feature of members of a particular species

Question 21

What happens if two organisms with different diploid numbers interbreed?

Answer 21

a) Unlikely to interbreed

b) Offsprings are infertile (Donkey 62 + Horse 64 = Mule 63)

Question 22

Chromosome number of:

a) Parascaris equorum
b) Oryza sativa
c) Homo sapiens
d) Pan troglodytes
e) Canis familiaris

Answer 22

a) 4
b) 24
c) 46
d) 48
e) 78

Question 23

Genome size of:

a) T2 phage 170,000 bp
b) E. Coli. 4.6 million bp
c) Drosophila melanogaster 130 million bp
d) Homo Sapiens 3.2 billion bp
e) Paris Japonica 150 billion bp

Answer 23

a) Viruses and bacteria tend to have very small genomes
b) Prokaryotes have smaller genomes than eukaryotes
c) Sizes of plant genomes can vary dramatically

Question 24

Chromosome number, genome size and genetic complexity

Answer 24

Chromosome number and genome size do not provide a valid indication of genetic complexity

Question 25

Number of genes and biological complexity

Answer 25

The number of genes present in an organism will differ between species and is not a valid indicator of biological complexity