Genetics test 1

chapters 1-6

Early Idea 1: Performationism

ca. 1650 Jon Swammerdam, inside the sex cell there is a fully formed adult which just enlarges (homunculus)

Early Idea 2; Pangenesis

ca. 1870 Charles Darwin, each part of the body contains genetic information for itself, gemmules carry information to the reproductive organs at contraception

Early Idea 3: Inheritance of Acquired Characteristics

traits acquired in an individuals lifetime become hereditary information, if my dads a painter i must be too, early idea of epigenetics

Early Idea 4: Blending Inheritance

offsprings traits are a blend of the parental traits like mixing paint

When was the Domestication of Plants and Animals

10,000–12,000 years ago

Germplasm Theory

Weismann 1892, cells in reproductive organs carry a full set of genetic information, which is passed to offspring

Cell Theory

Schleiden and Schwann 1839, all life composed of cells arrive from pre exisiting cells, fundamental unit of structure and function

Natural Selection

Darwin 1859, more about how animals evolved as opposed to humans survival of the fittest passes down the best traits.

Basic Principles of Hereditary

Mendel 1868, pea guy drastic results of parental genetics showed how genes move from parents to offspring

Chromosomes

Flemming 1879, observed the division of chromosomes and published an in depth description of mitosis

Genome

a complete set of genetic instructions for any organism

Histones

Positively charged proteins that bind to DNA to help keep it compact, and chromosomes are condensed around this. Specialization of function genes is like a circuit board

Genes on Chromosomes

Sutton 1902, discovered that genes are located on chromosomes

Alleles

multiple forms of a gene

DNA Structure

build by nucleotides, Adenine, Thymine, Guanine and Cytosine A=T G=C, complimentary base pairs

Central Dogma

DNA to RNA to Protein

3 Divisions of Genetics

transmission, molecular, and population

Model organisms

1. ability to be reared in laboratory equipment

2. production of numerous progeny

3. ability to carry out controlled genetic crosses

4. accumulated body of knowledge about genetic structures

ex. fruit fly, bacterium, mice

Prokaryotes

Circular DNA, smaller, little DNA, no membrane bound organelles, loose DNA

Eukaryotes

linear chromosomes, bigger, lots of DNA, Histones, membrane bound organelles, sexual reproduction

Homologous Pairs

Two organized sets of chromosomes found in a diploid organism, two sets of genetic information almost the same thinks sisters not twins

Sub-metacentric

when the centromere is the middle of the chromosome

Metacentric

when the centromere is close to the bottom half of the chromosome

Telocentric

when the centromere is closest to the top of the chromosome

Acrocentric

When the chromosome is closer to the top of the chromosome

Centromere

attachment location for the spindle microtubules

Telomeres

tips of linear chromosomes

Kinetochores

proteninaceous structures on top of centromeres, where microtubules literally attach (spindle microtubules look like noodles off the center part)

Origin of Replication

where the DNA synthesis begins

Cell Cycle

Interphase and M-phase

Interphase

Growth, DNA synthesis and chromosome replication phase

M-Phase

Division, mitotic and meiotic, phase checkpoints are the key transition points between parts of the cell cycle

Mitosis

prophase, metaphase, anaphase, and telophase.

prophase- chromosomes condense,

metaphase- where they align in the cell's center,

anaphase- where sister chromatids separate and move to opposite poles,

telophase- where new nuclei form around the separated chromosomes.

Meiosis 1

Separation of homologous chromosomes, diploid cells become haploid, metaphase and anaphase 1, and telophase

metaphase- random alignment of homologous pairs along the metaphase plate

Anaphase 1- separation of homologous chromosome pairs, random distribution into two newly divided cells

telophase- cleavage furrow two distinct cells.

Meiosis 2

Separation of sister chromatids, like meiotic division

same pattern as meiosis 1 but with 23 chromosomes instead of 46

Spermatogenesis

In male gamete production, four cells are produced. Meiosis 1 happens during the primary spermatocyte; Meiosis 2 happens during the secondary spermatocyte

Oogenesis

female gamete production, one cell produced, meiosis 1 happens during primary oocyte, meiosis 2 happens during secondary

Synapsis

close pairing of homologous chromosomes

Tetrad

closely associated 4 sister chromatids

Chiasmata

location where chromosomes touch/crossover

Crossing Over

sister chromatids touch and exchange genetic info

Why did Mendel succeed?

1. Had a good experimental model

2. Took an experimental approach and analyzed
   results mathematically

3. Studied 7 easily differentiated characteristics

Gene

An inherited factor that helps determine a charateristic

Allele

One or two more alternative forms of a gene

Locus

specific location on a chromosome occupied by an allele

Genotype

A set of alleles possessed by an individual organism

Homozygote

an individual organism possessing two of the same alleles at a locus

Heterozygote

An individual organism possessing two differnt alleles at a locus

Phenotype

The appearance or manifestation of a characteristic

Homologous Chromosomes

A pair of matched chromosomes (one paternal, one
maternal) in a diploid organism that are the same size,
have the same centromere position and have genes in the
same order

Monohybrid crosses

Crossing between one trait AA x aa

Phenotypic ratio: 3:1, 1:1 or uniform progeny

Genotypic Ratio: 1:2:1, 1:1 or uniform progeny

Dominant Traits

A genetic trait that will be expressed if at least one copy of the dominant allele

Recessive Traits

A genetic characteristic that is only expressed in an individual when they inherit two copies of the corresponding gene.

Principle of Segregation

During the formation of gametes (sex cells), the two alleles for a given gene separate, or segregate, from each other so that each gamete carries only one allele. Yellow or Green

Addition Rule

The probability of this or that happening

Multiplication Rule

Probability of this and that happening

Dihybrid crosses

crossing alleles with two traits, alleles of genes located on different chromosomes will sort independently

phenotypic ratio: 9:3:3:1

Independent assortment

that the alleles for different genes segregate independently of each other during gamete formation], meaning the inheritance of one trait does not influence the inheritance of another.

Chi Square Goodness of Fit Test

1. Calculate chi-square (know the formula red
   arrow)
   2. Find chi-square value on table using degrees
   of freedom (n-1)
   3. Interpret p-value (probability difference
   between O and E is due to chance)

anything lower than last two rows have no significant difference

Sex Determination Chromosomal

A genetic mechanism that determines an individual's sex based on the presence or absence of specific chromosomes, such as the XX/XY system in humans.

Genic Sex Determination

A biological system where an individual's sex is determined by a specific set of sex chromosomes, the ZZ/ZW system in birds, or by a single key gene like the SRY gene on the Y chromosome in mammals

Environmental Sex Determination

Temperature-dependent sex determination in reptiles like alligators and turtles, where nest incubation temperature determines the sex of the offspring

Pseudoautosomal Region

Where the chromosomal sex determination system pair, where the X and Y chromosomes are homologous but not totally homologous. Top and bottom tips of chromosomes.

SRY Gene

Produces a cascade of other gene products, “on switch” for male sex determination, and is on the Y chromosome. Starts Male Sex and is Y-linked

Non-Disjunction

When homologous chromosomes do not separate in meiosis.

Sex Chromosome Proportions

Punnet Squares using parental genes, should yield same phenotypic ratios as monohybrid crosses

Barr Bodies

Dark spots in cells, extra X’s in organisms that get turned off.

Complete Dominance

Heterozygote phenotypes matches homozygote phenotype.

Incomplete Dominance

“Blending” Phenotype of the heterozygote is intermediate (falls
within the rane) between the phenotypes of the two
homozygotes. 1:2:1

Co-Dominance

Phenotype of heterozygotes includes the phenotypes of both homozygotes. 1:2:1

Penetrance

The % of individuals having a particular genotype that expresses the expected phenotype.

Expressivity

The degree to which a trait is expressed. 6/10 purple

Lethal Alleles

Causes early stage death, some genotypes cannot appear because of this. Differs from mendelian expectations 2/3:1/3

Multiple Alleles

For a given locus, more than two alleles are present within a group of individuals. Think of duck coloration, multiple colors so three different allele types.

Gene Interactions

The effects of a gene at one locus depend on the presence of genes at other loci. They still exhibit independent assortment but do not act independently in their phenotypic expression. 9:3:3:1 ratio of one trait phenotype.

Cytoplasmic inheritance

Cytoplasmic genes, which are usually
inherited from only one parent

Genetic maternal effect

Nuclear genotype of the maternal parent. Genotype of mother determines the phenotype of offspring.

Sex Linked Characteristics

Genes Located on the Sex Chromosomes

Sex Influenced Characteristics

Autosomal genes that are more readily
expressed in one sex, expressed differently in both sexes.

Sex Limited Characteristics

Only on sex expresses the phenotype. Autosomal genes who are limited.

Imprinting

Differential expression of genetic material depending on whether it is inherited from the male or female parent, caused by methylation.

Epigenetic Modification

One gene can mask the effect of another gene, follow chemical pathways, and needs to have a dominant allele at each checkpoint to continue to exhibit the new trait.

4 main types: recessive, dominant, duplicate recessive, and duplicate dominant

Recessive Epistasis

9:3:4 phenotypic ratio

Dominant Epistasis

12:3:1 phenotypic ratio

Duplicate Recessive

9:7 phenotypic ratio

Duplicate Dominant

15:1 phenotypic ratio

Pedigree

A pictorial representation of a family history, a family tree that outlines the inheritance of one or more characteristics.

Autosomal Recessive Pedigree

appears equally in both sexes, tends to skip generations and more likely to appear among progeny of related parents

Autosomal Dominant Pedigree

Appears equally in both sexes, unaffected people do not transmit, affected people must have one affected parent.

X Linked Recessive Pedigree

An affected male will not pass to his sons but will to his daughter, she will pass this on to her sons and they will be affected. More frequent within males.

X linked Dominant Pedigree

Does not skip generations, all affected males will pass it to all their daughters (no sons), heterozygous affected females can pass it on to their daughters and sons but not always guaranteed to get it. 50/50.

Amniocentesis Sampling

1. needle is inserted into the amniotic sac

2. fluid is withdrawn

3. fetal cells are separated

4. cells are cultured and then tested on

Chorionic Villus Sampling

1. good for early pregnancy

2. catherer is inseted into the uterus

3. it is places into contact with the out layer of the placenta (Chorion)

4. a small piece is removed through suction and those cells are used for testing