Chapter 12 Intro to Genetics Biology

Homologous

Refers to chromosomes in which one set comes from the male parent and one set comes from the female parent. They are about the same size and genes are located in the same place

Diploid

A cell that contains two sets of homologous chromosomes. Called 2n

Haploid

A cell that contains only a single set of genes. (one parents) ex: sperm/egg have 23 chromosomes. Called n

Meiosis

The process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes. Process involved in Sexual reproduction for multicellular organisms

Tetrad

Structure containing four chromatids that forms during meiosis.

Crossing-over

The process in which homologous chromosomes exchange portions of their chromatids during meiosis. Occurs in prophase I. transfers genetic information between another

Genetics

The scientific study of heredity.

Fertilization

The process in sexual reproduction in which male and female reproductive cells join to form a new cell. Egg + Sperm = zygote which is haploid cell

Trait

Specific characteristics of an individual. (Ex tall/short)

Hybrid

Offspring of crosses between parents with different traits.

Gene

Sequence of DNA that codes for a protein and determines a trait; a factor passed from parent to offspring. Is found in chromosomes. They are portion of DNA having the ability to code characterstic/trait

Allele

One of a number of different forms of a gene which can be same or different. parents contribute 1. Represented by letters (TT/tt)

Principle of Dominance

Mendel’s second conclusion that some alleles are dominant and others are recessive.

Segregation

The separation of alleles during gamete formation.

Gamete

A sex cell.

Probability

The likelihood that a particular event will occur.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Phenotype

The physical characteristics of an organism.

Genotype

The genetic makeup of an organism. Example (TT,Tt,tt)

Punnett Square

A diagram that can be used to predict the genotype and phenotype combinations of a genetic cross.

Independent Assortment

One of Mendel’s principles stating that genes for different traits can segregate independently during the formation of gametes.

Incomplete Dominance

A situation in which one allele is not completely dominant over another allele.

Codominance

A situation in which the phenotypes produced by both alleles are completely expressed.

Multiple Alleles

A gene that has more than two alleles.

Polygenic Trait

A trait controlled by two or more genes.

Sexual Reproduction

requires two parental organisms and the production of sex cell/gametes in eggs and sperm cells. It is not genetically identical favoring genetic diversity.

Oogenesis

Egg

Spermatogenesis

sperm

genetic diversity →

adaptation(individual organisms) → (population) → evolution (species) 

How many phases in Meiosis technically

8 phases dealing with nuclear content/DNA/Chromosomes

Conceptually how many phases that we added?

11 phases (one interphase, two cytokinesis)

What problem would occur if there were two interphases

the second interphase would negate the process reducing the chromosomes by 50%

Interphase

Similar to Mitosis as its job is to grow as a cell and synthesize the DNA and replicate it

Prophase I

The nuclear membrane is dissolved and the DNA forms with the histones become chromosomes and condenseds and spindle fibers form similar to mitosis. In meiosis the chromosomes pair with its corresponding homologous chromosome. It forms a tetrad and would later undergo crossing over.

Metaphase I

Spindle fibers attach to the tetrad and the paired homologous chromosomes line up in the center.

Anaphase I

spindle fibers pull apart the homologous chromosomes separating the both of them to the opposite end of the cell.

Telophase I

Nuclear membrane forms around the chromosomes on both ends

Cytokinesis I

furrow forms and separates the two nuclear membranes forming two new cells that are haploid due to the cells not being fully completed chromosomes pairs.

Prophase II

Chromosomes of both cells only consisting of two chromatids each become visible and do not form a tetrad since homologous pair is already separated

Metaphase II, Anaphase II, Telophase II

All similar to one but the chromosomes are separated by the chromatid and nuclear membrane form producing four haploid cells

Morgan found that

Chromosomes is actually groups of linked genes and Mendals principle still holds true

Gene Linkage

Genes that are close together in the same chromosomes are more likely to be inherited together due to their close proximity

Gene Mapping

Alfred found that the farther the genes are in a chromosomes the more likely they are to cross over and based on this they can determine where the genes locations were

Mendal experimented on what

On peas in which he cross the eggs and sperm from the flowers that are usually producing its own seeds.

In genetic crossing we call the orginal parental what and the offspring what?

Parental = P Offspring = F₁ / first filial (Latin for son and daughter)

Mendals first principle is

an individual characteristic are determined by factors that are passed on from one parental generation to a another