Genetics - Linkage and recombination lectures 3-4

Question 1

complete dominance

Answer 1

the phenotypes of the heterozygote and the dominant homozygote are identical

Question 2

incomplete dominance

Answer 2

the phenotype of the f1 hybrids is somewhere between the two parental varieties

Question 3

codominance

Answer 3

two dominant alleles affect the phenotype in separate, distinguishable ways

Question 4

multiple alleles

Answer 4

most genes exist in more than one allelic form
for example, the gene for blood type.
This gene codes for the enzyme that adds either A or B carbohydrate to red blood cells.

Question 5

pleiotropy

Answer 5

when one gene affects the phenotype in multiple ways

Question 6

mendelian disorders

Answer 6

disorders caused by a single gene

Question 7

DNA damage and repair

Answer 7

our dna is constantly being damaged and repaired

Question 8

DNA ligase

Answer 8

an enzyme that repairs DNA

Question 9

meiosis 1

Answer 9

homologous chromosomes separate

Question 10

meiosis 2

Answer 10

sisters chromatids separate

Question 11

tetrads

Answer 11

four part structure that forms during prophase of meiosis,

consisting of two homolgous chromosomes

Question 12

crossing over/ recombination

Answer 12

in prophase one of meiosis, each pair of homologous chromosomes will slightly overlap and share and reshuffle dna at points called chiasma.

Question 13

synaptonemal complex

Answer 13

during prophase 1 . the two homologous chromosomes join together via a protein scaffold. this joins the chromosomes along their length.

Question 14

cohesion crosslinking

Answer 14

cohesion crosslinking occurs to hold the two chromosomes together and prevent them being pulles apart until anaphase.

Question 15

independent assortement

Answer 15

when genes are located on different chromosomes hence they are inherited separately

Question 16

complete linkage

Answer 16

when two genes are so close to each other on the chromosome that even crossing over will not separate them

Question 17

incomplete or partial linkage

Answer 17

when genes are far apart on a chromosome , hence crossing over may or may not affect them

Question 18

linkage

Answer 18

two genes are inherited together

Question 19

X inactivation

Answer 19

if the x chromosome of a mammalian female becomes inactive, the phenotype will be a mosaic of the two traits

Question 20

parental types

Answer 20

when the phenotype of the offspring is the same as the phenotype of the parent

Question 21

recombinants

Answer 21

when the phenotype of the offspring is a combination of the parents phenotype