L16 GENETICS II

Question 1

What is incomplete dominance?

Answer 1

Incomplete dominance is the heterozygous form of an individual where it is the intermediate of the 2 given forms.

Both alleles are expressed in incomplete dominance.

Question 2

In incomplete dominance, the WHAT always reflects the WHAT?

Answer 2

PHENOTYPE always reflects GENOTYPE.

Question 3

What is codominance?

Answer 3

Codominance is the phenomenon where two allelez are expressed in separate, distinguishable ways.

Question 4

What is a non-mendelian trait?

Answer 4

A trait that does not strictly follow the recessive/dominance rules.

An example is human height, it is varied between each person and each person has their own potential height range.

Question 5

TRUE OR FALSE: one pair of alleles always corresponds to one genotype.

Answer 5

FALSE: many alleles can code for one single gene.

these are polygenic traits!

Question 6

What is epistasis?

Answer 6

Epistasis is the phemonemnon where individuals can posess a gene that masks other genes on a different locus.

Think of albinism. They carry the dominant epistatic gene and express no pigment.

Question 7

What is Pleiotropy?

Answer 7

The expression of 2+ traits by a single gene.
.

Marfan syndrome is the mutation of the FBN1 gene and results in varied symptoms: elongated limbs, scoliosis, enlarged aorta, vision issues, connective tissue malfunctions.

Question 8

What is polygenic inheritance?

Answer 8

Polygenic inheritance is the phenomenon where multiple genes interact to express one unique trait. An example is skin colour and all its variations.

Question 9

Fill in the blanks.

Answer 9

Question 10

What is meant by sex-linked inheritance?

Answer 10

Sex-linked inheritance refers to the traits/characteristics influenced by genes found on the X sex chromosome.

Question 11

All children will inherit which chromosome?

Answer 11

All children inherit the X sex-chromosome from maternal. Their sex will depend on inheriting another X (female) or Y (male) chromosome from paternal.

Question 12

What is hemizygous?

Answer 12

Individual that has a gene without an allelic counterpart.

IE. Men will not have second allele for genes found on their X chromosome, they are considered hemizygous.

Question 13

What is polyploidy?

Answer 13

The precense of 2+ sets of chromosomes.

Question 14

What is aneuploidy?

Answer 14

Anomaly in chromosome numbers.

Question 15

Name the two types of aneuploidies.

Answer 15

Trisomy: Tri=3
Meaning 1 extra chromosome.
Monosomy: Mono=1
Meaning 1 missing chromosome.

Question 16

What is Disomy?

Answer 16

Disomy is having normal amount of chromosomes (Di=2)

Question 17

What causes aneuploidies?

Answer 17

Nondisjunction during meiosis.

Question 18

What is nondisjunction?

Answer 18

Nondisjunction is an abnormal division in meiosis where chromosome(s) fail to separate.

Question 19

Give an example of an aneuploidy.

Answer 19

Trisomy-21 is Down Syndrome. It means there is a third chromosome on pair #21.
The result is intellectual disability, sexual sterility, characteristic facial features.

Question 20

What is the only survivable monosomy in humans?

Answer 20

Turner syndrome: individual with only 1 X chromosome.

Question 21

TRUE OR FALSE: A gamete can survive with 1 Y chromosome, no X chromosome.

Answer 21

FALSE: all gametes need 1 X chromosome to survive.

Question 22

What is a barr body?

Answer 22

A metabolically inactive X chromosome.
It is a less severe aneuploidy.

Question 23

What is the purpose of a Barr body?

Answer 23

The purpose of a Barr Body is to ensure the amount of X-chromosome gene material remains the same between males&females.

Question 24

How many barr bodies in each?
XX
XXX
XXY
XY

Answer 24

1. XX= 1 barr body
2. XXX= 2 barr bodies
3. XXY= 1 barr body
4. XY= no barr bodies.

remember, women will always have 1 barr body by default.