chapter 17 - inherited change

Question 1

What is a genotype

Answer 1

A genotype is the genetic constitution of an organism [all of the alleles present in an organism]

Question 2

What is a phenotype

Answer 2

A phenotype is the observable characteristics of an organism. Or the bio chemical characteristics of an organism. [Expression of the genotype] and it’s interaction with the environment.

Question 3

what is an allele

Answer 3

an allele is a variant of a particular gene

Question 4

What is a gene

Answer 4

A gene is the length of DNA [a sequence of nucleotide bases]

Question 5

What is a Locus

Answer 5

It is the position of a gene on a particular DNA molecule

Question 6

What is homozygous/homologous chromosomes

Answer 6

It is where the allele on each of the chromosomes is the same and there are two Loci.

Question 7

What is heterozygous/heterozygous chromosomes

Answer 7

It is where two alleles are different on each chromosome

Question 8

what is the first filal generation

Answer 8

F1 generation. first generation from two parents

Question 9

what is the gregor mendel model

Answer 9

He studied the breeding of peas. And the color of pods of Pea plants [green and yellow]

Question 10

What is mono hybrid inheritance

Answer 10

It looks at how Alleles from a single gene are passed on from one generation to the next.

Question 11

Why is mono hybrid inheritance and a mono hybrid cross useful.

Answer 11

It can be used to make predictions about phenotypes of offspring from specific breeding pairs. There is an equal chance of the zygote inheriting either allele from their parents. These are called test crosses.

Question 12

What is a limitation of a mono hybrid cross

Answer 12

All of the predicted genotypes are based on chance, however real life results can differ from the test cross.

Question 13

Why is mono hybrid inheritance useful when finding an unknown genotype and how do you find an unknown genotype prediction from a mono hybrid cross

Answer 13

You would cross the unknown genotype with a homozygous recessive or homozygous dominant individual. And you would look at the outcomes and if there is a dominant allele in any of the F1 generations then the unknown genotype is either heterozygous or homozygous dominant.

Question 14

What does the basic law of genetics [the law of segregation] state

Answer 14

It states in diploid organisms characteristics are determined by the alleles that occur in pairs. Only one of each pair of allele can be present in a single gamete.

Question 15

What is dihybrid inheritance

Answer 15

It is were two different genes are inherited at the same time but on different chromosomes.

Question 16

Give an example of a dihybrid cross/dihybrid inheritance [Gregor Mendel model]

Answer 16

The shape of a seed [wrinkled]

The color of a seed [yellow]

Question 17

What is the ratio in the F2 generation of a dihybrid cross

Answer 17

9:3:3:1

Question 18

What is the law of independent assortment

Answer 18

It is where each member of a pair of alleles may come by and randomly with either or another pair.

Question 19

Why did Gregor Mendel choose pea plants to observe

Answer 19

Because they were easy to grow and possess many contrasting features that could easily be observed.

The results produced were quantitative

Question 20

What is co-dominance

Answer 20

Where both alleles are expressed in the phenotype

Also when both alleles are equally dominant. This means they are both expressed in the phenotype.

Question 21

What are multiple alleles

Answer 21

Where there are more than two alleles, of which two may be present at the loci of an individual’s homologous chromosomes.

Question 22

Give an example of codominant with flower colours

Answer 22

CWCW = white flowers 
CRCR = red flowers 

F1 gen / crossing them
100% of the genotype will be heterozygous and the phenotype for all will be pink

F2 gen
50% homozygous 50% heterozygous

Question 23

What is the multiple alleles

Answer 23

It is when sometimes a gene has more than two alleles, for example in blood groups

Question 24

Give an example of multiple alleles

Answer 24

Blood group, ABO blood groups. The three alleles associated with the gene [immunoglobulin] gives rise to the production of different antigens on the surface membrane of red blood cells. Leading to different blood types

Question 25

If possible genotypes of the three different blood alleles

Answer 25

A co-dominant
B co-dominant
O recessive

Question 26

give 4 blood groups

Answer 26

blood group possible genotypes
A. lAlA or lAlO

B. lBlB or lBlO

AB. lAlB

O. lOlO

Question 27

Can they be more than three alleles in multiple alleles.

Answer 27

yes. eg coat coat colour in rabbits example

Question 28

What is sex linkage

Answer 28

Sex linked genes are any present on one sex chromosome and not the other so the sex of an individual affects what alleles they pass on to the offspring through their gametes.

Question 29

How many phenotypes do males have and how many phenotypes to females have and sex linkage

Answer 29

Females have three phenotypes: normal, carrier, has the disease

Males have two phenotypes: normal and has the disease

Question 30

What is why linked disorder

Answer 30

It is where the male would inherit from their father, females won’t have the disease at all. the affected gene is present on the Y chromosome only

Question 31

Why are males more likely to have recessive conditions for example hemophilia

Answer 31

Males are more likely to have recessive conditions because they only require one copy of the sex linked recessive allele for expression. As a non-homologous portion of the X chromosome will appear more frequently in males as a X chromosome is longer than the Y chromosome

Question 32

From which parent do males inherit a sex linked condition from

Answer 32

from their mothers X chromosome

Question 33

What is haemopholia

Answer 33

It is a condition where the blood clots slowly and there may be slow and persistent internal bleeding especially in the joints. It could be potentially lethal if not treated.

Question 34

Why are they more hemophilic males than females

Answer 34

Hemophilia is a sex linked disorder. Males only require one recessive allele too have hemophilia in their phenotype. Where is females need to inherit two recessive alleles in order to have the condition.

Most females also die early on and I’m more affected during mensuration

Question 35

What is a pedigree chart

Answer 35

A pedigree chart is one useful way to Trace inheritance of sex linked characters such as hemophilia.

Question 36

What is autosomal linkage

Answer 36

It is the name given to the situation where two or more jeans are carried on the same autosome.

Question 37

which chromosome is not called an autosome

Answer 37

sex chromosome

Question 38

Why are offspring more likely to resemble the Parental genotype in autosomal linkage

Answer 38

two or more genes are located on different loci on the same chromosome. The closer to genes are to each other the less likely crossing over will occur. the further the genes are the more likely crossing over will take place. They are often less likely to be separated during crossing over, therefore the offspring inherits the genes together therefore they are more likely to resemble the parental genotype.

Question 39

What is it epistasis

Answer 39

Epistasis is the interaction between two genes were one gene masks the expression of the other gene in the phenotype.

Question 40

What is the suppressing gene

Answer 40

It is sometimes called the epistatic gene

it suppresses another gene, masking it in the phenotype

Question 41

What is the suppressed gene

Answer 41

the gene that gets masked. also called the Hypostatic gene.

Question 42

What is recessive epistasis

Answer 42

We’re two copies Of the recessive allele is required to mask Mask the expression of the hypostatic gene

Question 43

What is dominant epistasis

Answer 43

Where at least one copy of the epistatic gene is required to mask the expression of the hypostatic gene.