Inheritance D3.2 Flashcards
How is a zygote formed?
male and female gametes fuse, their nuclei join and double the chromosome number
What is inside of the zygote nucleus?
contains two chromosomes of each type and is therefore diploid with two alleles of each gene.
What are hybrids?
crossed
What is self pollination in plants?
grow male and female in the same plant
P-generation
the parental generation or the first-true breeding crossed
F1 generation
the first generation of offspring produced by crossing two true-breeding parents. they are typically heterozygous
F1 generation
crossing individuals from F1. often exhibits 3:1 ratio
Allele
alternate version of a gene that differs by one or a few bases and occupies the same locus on a chromosome
Law of segreation
only one of the two gene copies present in a diploid organism is distributed to each gamete that it makes during meiosis.
Genotype
the genetic makeup of the organism and codes for the phenotype. symbolic representation of a pair of alleles.
Phenotype
observable traits
Phenotypic plasticity
gene expression changes in order to become adapted to specific environmental conditions. it is reversible as alleles remain unchanged.
Phenyletonuria
genetic disease caused by a recessive allele of a gene, mutation of ene on chromosome 12 coding for the enzyme phenylalanine hydrolase. disruptions with neurotransmitters in the brain: mental disorders
Codominance
both alleles are expressed independently in the phenotype and are uniquely recognizable.
Roan
cows with red and white coats
Incomplete dominance
the action of one allele does not completely mask the other
What is codominance and incomplete dominance denoted by?
CW CR
Gene pool
the genes of all the individuals in a sexually reproducing population
What are some characteristics of the gene pool?
- only one copy of an allele can exist on each chromosome - an individual can only inherit two alleles rather than the full number available in the gene pool.
- contains many different alleles of a gene due to existence of multiple alleles caused by SNPs.
Single nucleotide polymorphism
an alternate version of a gene can be created.
- many different versions of a gene exist, there can be multiple alleles of any gene.
- nucleotide change
The existence of more than two phenotypes
some genes dont only have two alleles but three, four, five…
What is the existence of more than two phenotypes dependent on?
dominant/recessive/codominant/etc
What gene codes for the production of glycoproteins in ABO blood groups?
- i
- IA
- IB
Which sex chromosome is larger?
X, therefore Y contains less genes: some are unique to Y some are shared with X
Where is the SRY gene located on and what is it?
Y, sex determining region
What does the SRY gene do?
causes the gonads of a fetus to develop testes of a male. release of the testes determining factor from the embryo. undifferentiated goads turned into testes to release testosterone
Sex-linkage
inheritance of genes on sex chromosome
Characteristics of the sex-linkage inheritance
- typically carried on the X in the non-homologous region
- different from inheritance on autosomes because X is longer and carries more genes
Carrier
a person with heterogeneous genotype with a recessive allele of a gene that does not have an effect on their phenotype.
Haemophilia
recessive and x-linked result in lack of clotting factor being produced in blood plasma. clotting stops bleeding following an injury.
Characteristics of Haemophilia
- most common in menn
- prognosis poor = males did not live long enough to pass allele to female offspring
Pedigree charts
show patterns of inheritance in a family for a specific trait (phenotype). genotypes can usually be determined.
- tracking of many genetically inherited diseases
- deduction of an allele as recessive/dominant/etc
Autosomal recessive
both parents no BUT offspring is = recessive
both parents yes = all offspring yes
Autosomal dominant
both parents yes BUT offspring not = dominant
yes offspring must have at least one affected parent
X linked recessive
never father to son. more males than females. all males affected recieve from mom.
X linked dominant
all daughters from fathers affected will have the trait. son will only inherit from mom on her X since Y is inherited from dad. more females.
Continuous variation
a continuous range of types is possible, with no distinct categories so there are many possible phenotypes. it is influenced by multiple genes if there is a genetic cause. environmental factors may influence trait.
Discrete variation
separate categories of variation with no intermediates between them so there are few phenotypes. influenced by just one or most a few genes if there is a genetic cause. environmental no effect
Polygenic
three or more alleles contribute to inheritance. influenced by environment
Box and whisker plots
show difference in mean and range of a series of data.
Independent assortment
the part of each parent separate and only one allele passes from each parent to an offspring.
Which allele is inherited in independent assortment?
dependent on chance due to random orientation of chromosomes in metaphase I. any combination of gametes is possible and eqyually likely.
Autosomal gene linkage
the genes of an individual can be located on the same chromosome
Linkage group
all the genes that have their loci on the same chromosome type.
- linked genes may not follow independent assortment and are mostly inherited together.
- when sections of chromosome is exchanged in crossing over, diff alleles may swap positions leading to recombinants.
Behavior during meiosis of two alleles
depends on their proximity or closeness to each other. the closer together linked genes are positioned, the less likely transferring allele from one chromosome to another.
Recombinant
a chromosome or DNA with a new combination of alleles due to crossing over in meiosis. the combination of characters is diff from original parents.
How can frequency of recombinants be measured
by crossing individuals that are het for both genes to individuals that are hoo recessive for both.
What does Chi-Squared test determine?
difference between an observed and expected frequency distribution is statically correct
