Week 2 Flashcards
(28 cards)
What is codominance?
The full effect of both alleles can be seen in the phenotype of the heterozygote
What is a biochemical pathway?
Shows the different mutant strains and the supplements in the order from which all strains are blocked to all being active
Define incomplete dominance
Heterozygote is a blended colour
Define codominance
The effect of each allele can be seen in the heterozygote
Define prototroph
An organism that can grow on minimal media
Define auxitroph
An organism that requires a supplement to grow on minimal media
What is a reciprocal cross?
A second cross between a male of phenotype a and a female of phenotype b as well as a male of phenotype b and a female of phenotype a to determine sex or autosomal linkage
What is a metabolic pathway?
Chemical reactions in cells that occur in a step by step sequence
What is a metabolic block?
A block in metabolic pathway that prevents the natural production of an enzyme from occurring
What is a phenocopy?
A copy of an inherited condition that occurs from an environmental cause
E.g meromelia- limblessness, a phenocopy of this inherited disease occurs from taking thalidomide during pregnancy
What is pleitropy?
A single gene may affect many features of a phenotype
What is variable expression
Degree/ range in which a particular phenotype is expressed by individuals
E.g mild, moderate and severe
What is reduced penetrance?
The proportion of genotypes that show the expected phenotype
What is a lethal allele genotype mutation?
An allele genotype or mutation that results in death( may be lethal at different stages of development)
Recessive Lethal: death in homozygous state
Dominant lethal: death in homozygous and heterozygous state
What is a Karyotype?
Sorted chromosome sets
What is a karyogram?
A drawing of chromosomes with banding shown
What is aneuploidy?
Extra chromosomes but not a set
E.g trisomy 2N+1/2N-1
What is euploidy?
Extra sets of chromosomes
Polyploidy: 3N triploid, 4N tetraploid
What are the two types of chromosomes?
- autosomes
- sex chromosomes
What are the five sex determining mechanisms?
1 environment(sex determined at conception(
2 genes (sex may be altered after conception)
3 haplo/diploidy
4 balance of autosome to sex chromosomes
5 sex chromosomes
What are some examples of environmental sex determination?
Reptiles:
- temperatures of nest affect the proportion of males to females, the higher the temp the more males
Bonelia:
- the closer the offspring land to the proboscis of worm, the more likely they are to be male.
What is an example of genetic sex determination?
Drosophila
- particular genotype may change expected phenotype
While xx= female and xy= male
Change to mutant at transformer locus can change female phenotype/ lack of tra+/ presence of tra allele prevents expression of female phenotype
Therefore
Tra Tra; XX= phenotypically male
Tra Tra: XY= genetically male
What is an example of haplo/diploidy?
Honey bees
Females are diploid(2N) from fertilised eggs
Males are Haploid (N) from unfertilised eggs
Male is hemizygous because only has one allele at each locus
What is an example of sex chromosomes to autosome sex determination?
Drosophila:
Relies on the ratio of sex chromosomes to autosomes
Female= AAXX= 1 Male= AAX= 1/2
