chapter 17 - inherited change Flashcards
What is a genotype
A genotype is the genetic constitution of an organism [all of the alleles present in an organism]
What is a phenotype
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.
what is an allele
an allele is a variant of a particular gene
What is a gene
A gene is the length of DNA [a sequence of nucleotide bases]
What is a Locus
It is the position of a gene on a particular DNA molecule
What is homozygous/homologous chromosomes
It is where the allele on each of the chromosomes is the same and there are two Loci.
What is heterozygous/heterozygous chromosomes
It is where two alleles are different on each chromosome
what is the first filal generation
F1 generation. first generation from two parents
what is the gregor mendel model
He studied the breeding of peas. And the color of pods of Pea plants [green and yellow]
What is mono hybrid inheritance
It looks at how Alleles from a single gene are passed on from one generation to the next.
Why is mono hybrid inheritance and a mono hybrid cross useful.
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.
What is a limitation of a mono hybrid cross
All of the predicted genotypes are based on chance, however real life results can differ from the test cross.
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
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.
What does the basic law of genetics [the law of segregation] state
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.
What is dihybrid inheritance
It is were two different genes are inherited at the same time but on different chromosomes.
Give an example of a dihybrid cross/dihybrid inheritance [Gregor Mendel model]
The shape of a seed [wrinkled]
The color of a seed [yellow]
What is the ratio in the F2 generation of a dihybrid cross
9:3:3:1
What is the law of independent assortment
It is where each member of a pair of alleles may come by and randomly with either or another pair.
Why did Gregor Mendel choose pea plants to observe
Because they were easy to grow and possess many contrasting features that could easily be observed.
The results produced were quantitative
What is co-dominance
Where both alleles are expressed in the phenotype
Also when both alleles are equally dominant. This means they are both expressed in the phenotype.
What are multiple alleles
Where there are more than two alleles, of which two may be present at the loci of an individual’s homologous chromosomes.
Give an example of codominant with flower colours
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
What is the multiple alleles
It is when sometimes a gene has more than two alleles, for example in blood groups
Give an example of multiple alleles
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
If possible genotypes of the three different blood alleles
A co-dominant
B co-dominant
O recessive
give 4 blood groups
blood group possible genotypes
A. lAlA or lAlO
B. lBlB or lBlO
AB. lAlB
O. lOlO
Can they be more than three alleles in multiple alleles.
yes. eg coat coat colour in rabbits example
What is sex linkage
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.
How many phenotypes do males have and how many phenotypes to females have and sex linkage
Females have three phenotypes: normal, carrier, has the disease
Males have two phenotypes: normal and has the disease
What is why linked disorder
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
Why are males more likely to have recessive conditions for example hemophilia
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
From which parent do males inherit a sex linked condition from
from their mothers X chromosome
What is haemopholia
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.
Why are they more hemophilic males than females
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
What is a pedigree chart
A pedigree chart is one useful way to Trace inheritance of sex linked characters such as hemophilia.
What is autosomal linkage
It is the name given to the situation where two or more jeans are carried on the same autosome.
which chromosome is not called an autosome
sex chromosome
Why are offspring more likely to resemble the Parental genotype in autosomal linkage
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.
What is it epistasis
Epistasis is the interaction between two genes were one gene masks the expression of the other gene in the phenotype.
What is the suppressing gene
It is sometimes called the epistatic gene
it suppresses another gene, masking it in the phenotype
What is the suppressed gene
the gene that gets masked. also called the Hypostatic gene.
What is recessive epistasis
We’re two copies Of the recessive allele is required to mask Mask the expression of the hypostatic gene
What is dominant epistasis
Where at least one copy of the epistatic gene is required to mask the expression of the hypostatic gene.
