Notatki Danniego part 1

Question 1

Mendelian genetics: first law -

Answer 1

law of segregation

Two alleles at a locus
segregate into seperate gametes; half carying one allele and the other half, the other allele

Question 2

Mendelian genetics: second law -

Answer 2

law of independent assortment

During gamete formation, the segregation of alleles at one locus is independent of the segregation of alleles at any other locus

Question 3

Locus -

Answer 3

The site at which a particular attribute is located

Question 4

Allele -

Answer 4

The alternative forms of information present at that site

Question 5

Complementation -

Answer 5

Two strains of an organism with different homozygous recessive mutations that produce the same mutant phenotype, produce offspring with wild-type phenotype

Question 6

Codominance -

Answer 6

A relationship between two versions of a gene. Two dominant alleles - both phenotypically expressed completely
-> AB blood type

Question 7

Incomplete dominance -

Answer 7

One allele for a specific trait is not completely dominant over the other. Resulting in a third phenotype that is a combination of two dominant & recessive phenotypes
-> Red vs. white flowers and pink offspring

Question 8

Epistasis -

Answer 8

The interaction between two or more genes to control a single phenotype
-> Baldness phenotype supersades genes for hair colour

Question 9

Pleiotropy -

Answer 9

when one gene is responsible for or affects more than just the typical two alleles that usually code for a certain characteristic.
-> Blood type - A, B, O alleles

Question 10

Lethal Alleles -

Answer 10

When expressed cause aorganism to die. (gene involved is considered an essential gene)

Question 11

Aneuploidy -

Answer 11

having the wrong number of chromosomes

Question 12

Interaction between melanin and pigment and hearing

Answer 12

• albinos have pigment with sight/hearing
• melanin in the brain soaks up damaging ions produced in cell by loud sounds
• Africans have more melanin - more resistant to hearing loss through loud sounds
  - > Called gene-environment interaction

Question 13

Barr body -

Answer 13

The inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization in those species in which sex is determined by the presence of the Y chromosome

Question 14

Mendels second experiment: Dihybrid cross

p’ SSYY x wwgg
f’ All SWYG - > smoothe yellow heterozygotes

What result did he obtain by crossing f’ with each other?

Answer 14

f'':
Smooth Yellow - 9
wrinkled Yellow - 3
Smooth green - 3
wrinkled green - 1

Independent assortment!

Question 15

Knowing the no. of heterozygous loci (n), count the number of:

1. possible types of gamete
2. f2 (f’’) genotypes

Answer 15

1. 2^n

2. 3^n

Question 16

independent assortment: Can cross breed for useful characteristics

Answer 16

High yield/high resistance

Question 17

Flu viruses are recombinant:

Answer 17

• Bird flu and human flu can be harboured in pigs
  - > Pathogenes may mix and create a new strain
• Transmitted back to humans
  - > only by inhaling viral particles, not from eating pork
  - > human to human viral particles in the air

Question 18

Modifications of mendel:

- incomplete dominance

Answer 18

Aa aa Aa

• Tay Sachs disease - body poisons itself
• Hexosaminidase enzyme
• genetic counselling

Question 19

Modifications of mendel:

- codominance

Answer 19

• see both phenotypes independently

- sickle cell anaemia

Question 20

Modifications of mendel:

- multiple alleles

Answer 20

• eye colour
• ABO blood group antigens
• CF - deletion of an allele

Question 21

Modifications of mendel:

- lethal alleles

Answer 21

Yellow mice 1/2 Yy yellow
1/4 yy wild-type
1/4 YY dies

Question 22

Modifications of mendel:

- multiple loci (different loci have similar effects)

Answer 22

autism - multiple deletions but can be in different places and still cause autism (rare among women 10%)

Question 23

Sex limitation -

Answer 23

traits only in men/women eg.

• horned sheep
• breast cancer 5-6% due to a gene
• male patern baldness only in men

Question 24

Polygenic inheritance -

Answer 24

when one characteristic is enrolled two or more genes

-> eye colour, height, skin colour