bio 312 test 1 - williams

genetics

study of all aspects of genes

genes

fundamental unit of biological information

molecular genetics

deals with genes (physically) one or few at a time

genome

a complete set of genes for an organism

forward genetics

The classical approach to genetic analysis, in which genes are first identified by mutant alleles and mutant phenotypes and later cloned and subjected to molecular analysis.

wild type

the phenotype for a character most commonly observed in natural populations

mutant

rare exceptional phenotype for a trait

reverse genetics

a form of genetic analysis that manipulates DNA to disrupt or affect the product of a gene to analyze the gene's function

hox genes

series of genes that controls the differentiation of cells and tissues in an embryo

electrophoresis

DNA, RNA, and protein molecules can be separated by size through a gel matric driven by electromotive force through electric field

southern blot

uses a "labeled" DNA probe to identify a specific piece of DNA out of a complex mixture of DNA

northern blot

uses a "labeled" RNA probe to identify a specific piece of RNA out of a complex mixture of RNA

western blot

uses a "labeled" antibody that specifically interacts with one proetin to identify that protein from a complex mixture of protein

polymerase chain reaction

primers detect and amplify a specific genomic region and DNA polymerase enzyme copies the segment thousands of times

law of equal segregation

mendels first law

during meiosis, the gene pairs seperates equally when making gametes

restriction fragment length polymorphism

the length of a restriction fragment, A DNA segment that results from the cutting of DNA by a restriction enzyme. way of characterizing and tracking a segment of DNA to use

null allele

A mutant allele that has a complete loss of normal function.

leaky allele

a mutant allele that has some, but not all of the wild-type function

silent allele

a mutant allele that has no effect on normal function, appears the same as wildtype.

haplosufficient

For a particular gene, one functioning copy is enough for a wildtype phenotype.

haploinsufficient

For a particular gene, one functioning copy is not enough for a wildtype phenotype.

test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

dihybrid cross

9:3:3:1

monohybrid cross

3:1

SRY gene

Y linked gene that triggers the male sexual development pathway

pseudo-autosomal region

small region on the X and Y chromosomes that contains homologous gene sequences

hemizygous

the presence of only one allele for a characteristic, as in X-linkage

autosomal recessive

appears in progeny of unaffected parents

both males and females affected

skips generations

rare disease

we assume that unlikely for those what mate into a family to be homozygous dominant for not having the affected allele

autosomal dominant

affected males and females in each generation

males and females transmit the condition in equal proportions

Polymorphism

The coexistence of two or more common phenotypes

x linked recessive

males are more frequently affected

affected males have unaffected sons and unaffective daughters that are carriers

unaffected sons of affected males will not pass on the condition

x linked dominant

affected males pass condition to all daughters and not sons

affected heterozygous females married to unaffected males pass condition to 1/2 sons and 1/2 daughters

y linked disorder

father to son transmission

maleness is an example

law of independent assortment

mendel's second law

gene pairs assort independently during meiosis

metaphase 1 of meiosis

crossing over occurs - chromosomes break and exchange in pairs

hybrid vigor

refers to situation where f1 is larger and more vigorous

carothers study

Independent assortment of chromosomes was supported by ratios of alleles and traits seen in progeny but how it occurred was done during this study of grasshopper testes.

observed the two chromosomes segregating with the same frequency

supported mendels second law

recombinant frequency of 50%

indicates that the genes are independently assorting and are most likely on different chromosomes

polygenetic inheritance

two or more genes contribute to the phenotypic expression of a single characteristic

discrete trait

The existence of distinct phenotypes for a given trait. Ex. Green vs Yellow peas.

continous trait

trait can take any value between phenotype extremes. ex - bp, height

quantative traits

quantative trait loci

polygenes

interacting gene that contributes to phenotypic variation for a trait

bp, weight gain

heteroplasms

sometimes a cell contains a mixture of genetic mutant and normal organelles

cytoplasmic segregation

The asymmetrical distribution of cytoplasmic determinants in a developing animal embryo.

ex - variagated leaves

cytoplasmic mutation

disorder is passed from mother to almost all children

affected fathers have unaffected children

linked genes

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

recombination

the genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division

bateson and punnett

British scientists who retrieved data which did not correspond to classic Mendelian ratios; led to the discovery of linkage and crossing over

thomas hunt morgan

proposed gene linkage as a hypothesis to explain the co inheritance of certain gene alleles

recombination frequency

the percentage of recombinant offspring among the total

Rf below 50%

when two genes are close together on the same chromosome (linked) they do not assort independently

cis conformation

two dominant or wild type alleles are present on the same homolog

trans conformation

the two dominant alleles are on different homologous chromosomes

Creighton and McClintock

studied two genes of corn they knew were both on chromosome 9

found that all the recombinants inherited one or the other of the two chromosomes depending on their recombinant makeup

A precise correlation between the genetic event of the appearance of recombinants and the chromosomal event of crossing over.

chromatids

crossing over is between these

tetrad analysis

The analysis of genetic linkage by analysis of different tetrad segregation types.

map units

A measurement of the distance between genes; one is equivalent to a 1 percent recombination frequency.

three point test cross

A test cross where one parent is heterozygous for 3 genes. Used in linkage analysis and gene mapping.

SNPs

difference in one particular base pair

considered silent

single gene inheritance pattern

humans have million

often found between two genes

some cause the presence or absence of a restriction enzyme

minisatellie markers

repeat units are 15-100 nucleotides in length

microsatellite markers

repeat units are a few nucleotides in length