Genetics Exam 1

used cytoplasmic and nuclear donor of nucleus and mammary cells to create the first instance of successful mammal cloning

17th and 18th century idea that humans develop from miniature versions of themselves that are either in the egg (ovist), or sperm (spermist) - now discredited (obviously)

outdated theory that traits from each parent were blended onto offspring

cross-breed them easily, multiple characters, short lifespan, big sample size (high reproductive rate & self fertilization)

cut off anthers of one flower, transfer anthers from another flower into the original flower’s stigma, plants seeds in peas

height, flower color & position, seed color & shape, pod color & shape

when individuals with a particular trait are bred together and offspring have the same trait as parents (trait is homozygous)

A monohybrid cross is a genetic cross between two individuals that differ in only one trait. Single gene/allele from each parent.

bred two true breeding parents of different parents, found all offspring had one trait, and amongst the offspring self fertilizing, the more common trait was present 3:1

Mendel - hereditary traits are determined by discrete units called genes, which are passed from parents to offspring. Genes are individual and do not blend in reproduction

Genotype refers to the genetic makeup of an organism (allele combination), phenotype are physical characteristics.

A gene is a segment of DNA with specific instructions for building a protein. An allele is a variant form of a gene.

homozygous two identical alleles. heterozygous two different alleles

dominant masks recessive. dominant is expressed if one allele is present, recessive is only expressed if both alleles are recessive.

A somatic cell is any cell in the body except for reproductive cells (diploid & mitosis). Gametes are reproductive cells (gamete and egg, haploid & meiosis).

diploid cells have two sets of chromosomes, one from each parent. haploid cells have one set of chromosomes.

two alleles for a given gene segregate away from each other during the production of gametes (think of diploid to haploid) - tells you that the segregation is random

we can predict offspring traits and better understand genetic inheritance

Dominant phenotype individual, cross with a recessive phenotypic individual to know if the dominant phenotypic individual is homozygous or heterozygous

diploid parent cell forms two diploid daughter cells (daughter cells look genetically identical)

Mitosis

G1, S, G2

DNA replication

cell growth, protein synthesis, checkpoints (G1 checks mitotic issues, G2 checks replication errors)

approx. 24 hours

certain genes located close to each other on the same chromosome tend to be inherited together (wrong)

different PAIRS of genes (alleles) separate independently into gametes during meiosis. (correct)

breeding including two different traits (genes) that are located on separate pairs of homologous chromosomes

9:3:3:1

refers to the presence of multiple variations (alleles) of particular genes within a population

most prevalent alleles, promotes reproductive fitness, DOES NOT MEAN DOMINANT, there can be more than one wild type allele

non wild type alleles, commonly recessive, can be dominant (gain of function allele, dominant-negative allele)

during DNA replication (common but many are inconsequential)

blocks activity (screws up as a protein), blocks folding, blocks transcription of a particular enzyme,

type of mutant allele that results in a gene having a new or enhanced function when compared to the wild type allele

mutant allele that can negatively effect the ability of the wild type allele to function

a dominant allele mutation that exhibits incomplete penetrance

individuals carrying a specific genetic mutation do not always express the expected phenotype

the range of a allele (gene’s) phenotypic expression in an individual

growth, DNA replication, cell functions (cells spend most of their time here)

condensed DNA and proteins

part of a chromosome where sister chromatids are held together

strands of replicated chromosomes

(before) nucleus is present, chromosomes are condensing, nuclear membrane/envelope is beginning to break down, spindle fibers/microtubules begin to form and extend from opposite ends of the cell, centrioles present

(middle) chromosomes align at the middle of the cell, spindle fibers attach to chromosome’s (two sister chromatids) centromeres (kinetochore region). Metaphase plate forms, bivalent attachment occurs

sister chromatids separate and are pulled to centrioles by spindles

spindles break down, nuclei reforms

sister chromatids are like identical twins of a single chromosome (same color and shape) while homo chromosomes are not identical, but work together (similar shapes, usually different colors unless it’s after replication)

organelles commonly found on opposite ends of the cell that contain microtubules

contains a pair of centrioles, organizes microtubules

protein structure that forms on centromere region of a chromosome

tells where cytokinesis will occur later

proper and stable attachment of homologous chromosomes to the microtubules of the spindle

cleavage furrow forms and cytoplasm is eventually divided into two and two daughter cells are formed that are genetically identical to parent

animal cell protein that is responsible for forming a contractile ring (cleavage furrow process) in cytokinesis

due to a rigid cell wall, a cell plate is formed instead of a cleavage furrow to separate two daughter cells

two sets of homologous chromosomes that are each similar in color, and each contain two sister chromatids

DNA replication & metabolic activity

chromosomes condense, thicken, align with homologous pairs - CROSSING OVER occurs

chromosome pairs align at middle of cell

spindle fibers pull away chromosome pairs to opposite sides of the cell

nuclear envelope reforms, revealing two distinct nuclei

spindles begin to form in each distinct nuclei

chromosomes align in the middle of each distinct nuclei

sister chromatids are pulled to opposite ends the cell by spindle fibers (each chromatid is now a referred to as a chromosome)

nuclei reforming, two cells divide into four cells

karyokinesis is the division of the cell nucleus and separation of chromosomes while cytokinesis is the division of the cytoplasm and separation of other cellular components

law of independent assortment

law of segregation

for a given gene, the dominant allele completely masks the other allele

neither allele is completely dominant over the other, in which heterozygotes display a phenotypic blend

homozygous recessive disease, but individuals who are heterozygous only have about half of normal enzyme function that of a normal individual (on a genotypic-molecular level)

heterozygous genotype when viewing two different genes, has higher selective advantage/reproductive fitness

Ss heterozygous individuals have an advantage against both non sickle cell, and being malaria resistant. While homozygous dominant are at a disadvantage having no malaria resistance, and homozygous recessive being full sickle cell disease

highly unrelated individuals mate, offspring will be heterozygous at most loci, often healthy and vigorous. ex: hybrid corn and mutts

two closely related individuals mate, many of same alleles, offspring are homozygous at many loci, often less vigorous, high incidence of recessive genetic disease

two dominant alleles, in which phenotypes are both expressed, neither of which are compromised.

disease resistance, versatility in dimer formation (enzyme functional diversity), variation in functional activity

blood types with a mix of genotype (ex: IA & IB), express both type A antigens and type B antigens, and neither are compromised

depending on blood type, your body produces anti antigens for the blood type you do not have (note: type O can give their blood to anybody b/c they have no A or B antigens)

genes responsible for certain traits are located on sex chromosomes

in males, sex chromosomes are XY, and these chromosomes are very different from each other

impacts male skin, making it scaly, on X chromosome

in two crosses, first take a affected male and breed with a unaffected female, then, in the reciprocal cross, take a unaffected male and breed with a affected female. if ratios are different between crosses, it tells you the gene is X linked

can impact both males and females

exclusively impact males

genes only found on Y chromosomes

found on Y chromosome in mammals, gene activation causes testosterone boost to signal male sex development

fake autosomal inheritance so it looks autosomal, but truly is not

of pseudoautosomal gene

trait influenced by what sex you are, commonly found in heterozygotes

scurs in cattle, Sc Sc = scurs in both sexes, but Sc sc = scuts in males only.

only seen in one sex & never in another (ex: physical appearance differences)

one gene that is responsible/contributes to multiple different phenotypes

pleiotropy

one gene can modify the effects of a completely different gene (multiple genes contributing to a common pathway)

phenotype of purple pigment is only expressed when complementation occurs in white pea plants

non mandelian inheritance pattern, only thing that influences phenotype of offspring is the genotype of the mother

data observed are the result of random chance alone

x^2 = (o-e)^2/e