Genotypes and phenotypes Flashcards
genotype
it describes an organism’s complete set of genes eg. Bb, BB
Phenotype
the observal features, traits or outward expressions of a gene eg. brown eyes
Dominant genotype
repersented by a capital letter and usually expressed in a heterozogous individaul.
Reccesive genotype, what is it masked by
rerpesnteed by a lowercase letter,usually masked by the dominant trait in a thereotzogus indivulda eg for blue eyes B is domiant in Bb
when is the recessive genotype expressed
shown if two alleles are expressed for exmaple bb in blueeyes
heterozogous
When two different alleles are inherited.
For example, Bb (Brown eyes)
homozogous
Two identical alleles from their mother and father.
For example, BB (brown eyes) or bb (blue eyes)
Codominance
Codominance
both alleles are dominant and are expressed in the genoype of anindivual eg blood type
when does codominance occur
when both alleles from the genotype are fully expressed in the phenotype of a heterozygous individual.
incomplete domiance
Incomplete dominance occurs when neither allele from the genotype is fully expressed, resulting in a ‘blending’ of traits eg. for flowers an example of incmoplete domaince is C^r C^w
how is the sex of an indiivudal determeidn
is determined by what sex chromosome is contained within the egg and sperm at fertilization.
what determines the gender of an indiivudal
The sperm determines the sex of the offspring as males can produce sperm containing either X or Y chromsome whereas females can onlyproduce gametes containing X chromsomes
Sex linked inheritance are either inherited from and what does sex inheritnace include
X or Y chromosome
colour blindness, haemophilia, baldness.
Why do more men have disorders linked to sex linked inhertiane
Since males only have one X chromosome, they are unable to mask the recessive trait, so therefore are expressed.
what factors can influence genotyeps
the environemnt can dramatically effect the way genes express themselves in genotypes eg. if you were raised in a place where you lacked essiental nutrients and were manlourished then your frame and bone structure will be smaller and weaker than someone who grew up well off and noursihed.
Proportionate heritability
Proportionate heritability
is Where an organism’s phenotype is explained partially by genes and partially by environmental factors
example of Proportionate heritability
the colour hydrangeas are dependent o the PH of the soil they are produced in
eg. putting alkaline soil will cause the flower to become pink whereas acidicifc soil will cause the flower to become blue and basic soil will cause the flower to become purple
An example of how the enviornment effects phenotype in refercne to point colouring
Tyrosinase is an enzyme that is repsonsible for melanin production, himalayoan rabbits are homozngous fora rescessive allele of the tyrosiane gene, therefore their born with white fur but when exposed to colder envornmrents they are partially black.
epigenticis
the study of heritable phenotypes changes that do not involve alterations in the DNA nucleotide sequences
examples of epigentic mechanissms
methylation of histones which tell the cell decrease/slowly down gene transcription, thus decreasing gene expression
Acetylation of histones which tells the cell to increase/quickening gene transcpriton/quickening thus increasing gene expression
why does having sickle cell anemia protect you from malaria
1.INCREASED MALARIA RESISTANCE AS IMMUNE SYSTEM IS ABLE TO IDNEITYF WHICH CELLS HAVE BEEN AFFECTED BY MALARIA QUICKER
2.harder for malaria to grow
differienate betwene homologous chromsoomes and sister chromatids
homologous chromeomse are a pair of chormoems wiht the same lenght and size, gene and gene loci and have the same centromre position, wheras sister chromatids are 2 chromomes held togheter by a centromeree
what is meant by sex linked inheritance
what stage are chromomes visible
prophase
d
synapisis
pairing of homologus chromomes to allow genes to swap-fusion ofgenes–process that allows crossing over to occur
compare what kind of cell is produced during meiosis to mitosis
meioiss-gametes
mtipsis-somatic cells
nature vs nurture
how epignetics work
The environment changes the way that the genotypes are expressed but does not change the sequence of the DNA.
differnce between genetics and epigentics
epignecites does not alter DNA nucleotide sequence
wh
why does methalyation of histones decrease gene transcritpion but aceytlation of histones increase gene transcirption
HISTONE MODIFICATION -> Methylation of the histone tails will cause increased wrapping of the DNA around the histones causing silencing of the dna
actyheltiaton of hitsiones–opposite
wh
why are epigentics important
it allows usto respond to the enviornemnt around us and adapt to it which increases our chances of survival
is there somatic transmission in epigentics
it is somatically hertiabble and someepigentic changes may be passed onto offspring.
