bio 93 final kms (genes stuff)

gene

unit of hereditary info w/ specific nucelotide sequence in DNA

alleles

alt. form of gene, same locus on homolog chromo

Law of Segregation

2 alleles for each character segregate into different gametes, during metaphase 1

Independent Assortment

Each pair of alleles segregates independently of other pairs during gamete formation, during anaphase 1

Law of probability, multiplication rule:

calculate probability of independent genetic events

Law of probability, addition rule:

calculate probability of more than 1 mutually exclusive genetic event.

Incomplete Dominance

produces intermediate blend of two parents,

Hypercholesterolemia

example of incomplete dominance (Hh), inherit one faulty gene (h) = less LDL receptors = higher cholesterol

Codominance

both alleles affect phenotype, in diff ways

ABO blood types

example of codimnance, IA and IB are co-dominant, and both are dominant over i, AB blood type receives no A and B antibodies, i receives both A and B antibodies

H antigen

Acts as the "base" or "starting" carbohydrate structure for creating A and B antigens

Pleiotrophy

When gene affects more than 1 phenotype character

Sickle cell anemia

example of pleiotrophy, a single mutation in DNA causes multiple, seemingly unrelated symptoms and complications throughout the body

Epistasis

gene at 1 locus alters phenotype expression of gene at 2nd locus, resulting in non-Mendelian inheritance pattern

dog coat color

The E/e gene, which is epistatic to the B/b gene, controls whether or not pigment of any color will be deposited in the hair.

Polygenic Inheritance

when a single trait is controlled by multiple genes (polygenes) rather than just one, resulting in a wide, continuous range of possible outcomes (phenotypes) instead of distinct categories

skin shades

example of polygenic inheritance, cross between 2 AaBbCc individuals would produce offspring covering wide range of shades, produces normal distribution of phenotypical range

Environment

product of genotype is a norm of reaction (range of phenotypic possibilities), determined by environment, broadest for polygenic characters

multifactorial chracters

traits influenced by both multiple genes and environmental factors quantitatively

Epigenetics

a mini primer, how environment turn genes on and off without altering DNA

Royal jelly

example of epigenetics, royal jelly diet turns on queen gene in regular bee

colorblindness

more common in men b/cuz the most common forms of colorblindness are inherited as an X-linked recessive trait, meaning the defective gene is located on the X chromosome, females have X to override x

White Eye Inheritance only in males

Results provided evidence that a specific gene is carried on a specific chromosome. Genes located on a sex chromosome exhibit unique inheritance patterns.

Gene Linkage

genes on same chromosome that tend to be inherited together in genetic crosses, not sex-linked

Recombination Frequency

the percentage of offspring that show a new combination of alleles for two genes, a measure of the distance between genes on a chromosome (recombinants/total offspring)

Crossing over

breaks linkage between genes on same chromosome

sex-linked recessive inheritance

mutation usually on x chromosome, causes a disorder more often in males (XY) because they only have one X, while females (XX) often remain healthy carriers due to their second, normal X chromosome masking the effect

Barr Body

condensed (de-methylated) x chromosome in females, serving to equalize gene expression (dosage compensation) by inactivating extra X's

Hypohidrotic ectodermal dysplasia

example of barr body dependence inheritance, hetero for sex-linked trait = half of cells express one allele while other half express other allele,

Epigenetics patterns

changing chromatin strucutre to turn off gene expression

genome imprinting

example of epigenetics, during gamete formation, silencing of one allele of certain genes

Prader-Will syndrome

example of genome imprint: set of genes on chromo 15 is unexpressed on Paternal chromosomes

Angelman syndrome

example of genome imprint: set of genes on chromo 15 is unexpressed on Maternal chromosomes

Translocation

alteration of chromosome, move segment from 1 chromo to nonhomo chromosome, ex: BCR-ABL oncogene, producing a hyperactive tyrosine kinase that constantly signals cells to divide

Chromatin

complex of DNA/Protein, found in nucleus of euk. cell

Histone

protein responsible for 1st level of DNA packing in chromatin

Euchromatin

loosely packed chromatin

heterochromatin

during interphase, highly condensed centromeres and telomeres = gene info harder to express

Transcription Histone Acetylation

promote gene expression, acetyl groups are attached to positively charged lysine’s in histone tails

DNA methylation

reduce gene exp, genomic imprinting

Transcription factors

proteins that initiate transcription, assists RNA polymerase

Activator

binds to enhancer and increases transcription

mRNA degredation

shortening polyA tail, remove 5’ cap, nuclease enzymes chew up mRNA

Initiation of Translation

can be blocked by regulatory proteins, bind to 5’ UTR, prevent ribosome attachment

Proteasome

bind proteins and degrades them

cell determination

process by which cells become specialized

morphogenesis

process where cells develop physical structure

cytoplasmic determinant

Maternal substances in egg that influence early cell development

Induction

signal molecules from embryonic cells development cause transcription changes in target cells

cell differentiation

after determination, marked by the production of tissue-specific proteins

MyoD protein

produce proteins that commit the cell to becoming skeletal muscle, a transcription factor that binds to enhancers of various
target genes

Bicoid

gene for pattern formation, a higher concentration of bicoid is required for head development compared to thoracic developmen

Fertilization

1st stage of embryonic development, egg fuse with sperm (haploid to diploid)

Cleavage

2nd stage of embryonic development, rapid divisions that transform a single-cell to a multicellular embryo without increasing the embryo's overall size

gastrulation

3rd stage of embryonic development, mass cell movements to make 3 germ walls

Organogenesis

4th stage of embryonic development, localized changes in tissue and cell shape, give rise to organs

blastomeres

smallers cells from cleaveaged cytoplasm of large cell

blastula

ball of cells with a fluid-filled cavity called a blastocoel

notochord

during organogenesis, notochord forms from
mesoderm, and the neural plate
forms from ectoderm

neural tube

become central nervous system

Neural Crest cells

develop along neural tube, form parts of embryo