cytogenetics

Question 1

what is cytogenetics?

Answer 1

the study of whole chromosomes (structure, number, morphology etc) in order to understand how they can lead to specific disorders

Question 2

How is a karyotype produced?

Answer 2

to study chromosomes of a single organism, geneticists arrange micrographs of the stained chromosomes in homologous pairs of decreasing size to produce a karyotype

Question 3

What aids karyotyping?

Answer 3

chemical stains such as quinacrine and giemsa can be used to differentially stain chromosomes to reveal species specific banding patterns

Question 4

what are telomeres?

Answer 4

caps of the chromosomes which protect the chromosome from being condensed after cell division

Question 5

all genes in the euchromatin can be easily transcribed, true or false?

Answer 5

true

Question 6

What can human metaphase chromosomes be categorised by?

Answer 6

length of the arms and centromere location

Question 7

How are metacentric chromosomes identified?

Answer 7

have short and long arms of roughly equal length with the centromere in the middle

Question 8

How are submetscentric chromosomes identified?

Answer 8

have short and long arms of unequal length with the centromere more towards one end

Question 9

how are acrocentric chromosomes identified?

Answer 9

have a centimetre very near one end and have small short arms - have secondary constructs on the short arms that connect very small pieces of DNA to the centromere

Question 10

What does ploidy mean?

Answer 10

something with ploidy on the end refers to the number of chromosomes

Question 11

how do you refer to an organism with 2 sets of chromosomes?

Answer 11

diploid cell

Question 12

how do you refer to something with one set of chromosomes?

Answer 12

haploid cell

Question 13

How many chromosomes does a human have?

Answer 13

23 pairs (46 in total)
22 pairs of autosomes
1 pair of sex chromosomes (XX and XY)

Question 14

How do diploid cells reproduce?

Answer 14

By mitosis making daughter cells that are exact replicas
e.g. of cells include skin, blood, muscle cells (somatic cells)

Question 15

What are haploid cells the result of?

Answer 15

the process of meiosis, a cell division which diploid cells divide to give rise to haploid germ cells
cells used in sexual reproduction (egg and sperm)

Question 16

What does polyploidy mean?

Answer 16

multiple sets of chromosomes are present
common in plants but rare in animals

Question 17

What are some types of numerical abnormalities?

Answer 17

polyploidy (triploidy, tetraploidy)
aneuploidy (trisomy, mono song, tetrasomy)
mixoploidy

Question 18

what are some types of structural abnormalities?

Answer 18

deletion
inversion
duplication
insertion
ring
translocation
isochromosome

Question 19

what is reciprocal translocation?

Answer 19

segments from two different chromosomes have been exchanged

Question 20

what is robersonian translocation?

Answer 20

an entire chromosome has attached to another at the centromere

Question 21

what is non-disjunction?

Answer 21

major occurrence in meiosis
the failure of homologous chromosomes or sister chromatids to separate during meiosis
abnormal number of chromosomes may result

Question 22

what determines the sex in Drosophila?

Answer 22

by the number of X chromosomes
there is no Y chromosome - XX is female X0 is male

Question 23

What triggers testes formation in mammals?

Answer 23

SRY- encodes a protein testis-determining factor

Question 24

What is male and female sex in birds?

Answer 24

make homogematic - ZZ
female hetergamatic - ZW

Question 25

how does environment determine sex?

Answer 25

occurs in some reptiles
sea turtles lay their eggs on the beach for temperature-dependent sec determination