Grade 11 Biology: Genetics

Interphase

-Cell is metabolizing and growing

-All organelles double, including DNA

Prophase

-Nuclear membrane and nucleolus disappear

-Chromosomes condense

-Centrioles move to opposite poles

Cytokinesis

-Divides the cytoplasm of parental cell into two daughter cells

-occurs in both mitosis and meiosis

P generation

Parent generation

F1 generation

Offspring of the parent generation (First Filial generation)

F2 generation

Offspring from a F1 x F1 cross (Second Filial generation)

Gregor Mendel

Father of Genetics; conducted experiments using pea plants

Metaphase

-Chromosomes move to the equator via centromeres attached to a spindle fibre

Anaphase

-Spindle fibres contract pulling sister chromatids to opposite poles

Telophase

-Nuclear membrane and nucleolus reappear

-Chromosomes relax; cytokinesis occurs

Gene

A segment of DNA on a chromosome that determines an inheritable specific characteristic.

Alleles

Different variations of the same gene

The Law of Segregation

For each trait, an organism carries two genes; one from each parent. Parents donate only one copy of each of their genes ( creating alleles)

Dominant

Allele that is visible regardless of the other allele being dominant or recessive and is represented by an uppercase letter in the genotype

Recessive

Allele that is only expressed when two recessive alleles are present, but masked (hidden) when a dominant allele is present and is represented by a lowercase letter in the genotype

Phenotype

Observable (physical) characteristics resulting from the combination of alleles in the genotype

Genotype

Specific combination of alleles of a trait in an organism represented by a set of letters

Homozygous

A combination of alleles where both alleles in the set are identical

Homozygous Dominant

A set of dominant alleles that are identical

Homozygous Recessive

A set of recessive alleles that are identical

Heterozygous

A combination of alleles where the two alleles are different with one dominant allele and one recessive allele

Monohybrid Cross

A simple genetic cross where the parents have different alleles of a specific trait

Punett Square

Simple grid that is used to represent the possible genotypes of offspring in monohybrid crosses

Dihybrid Cross

A genetic cross where the parents have different alleles of two specific traits

The Law of Independent Assortment

Two alleles of one gene segregate without influencing the segregation of two alleles of a different gene and the probability of the phenotype of the offspring will always have the ratio 9:3:3:1 regardless of which two genes

Complete Dominance

One trait fully dominates and is expressed in the phenotype

Incomplete Dominance

Heterozygote has an intermediate trait between the dominant and recessive phenotype due to neither of the alleles fully dominating the other and this is represented by superscript in the genotype

Codominance

Heterozygote fully expresses the traits of both alleles and this is represented by only having captial letters in the genotype since there is no recessive allele

Multiple Alleles

When there are more than two variations of the same gene

Sex-Linked Inheritance

Traits controlled by genes located on the sex chromosomes

Autosomes

A chromosome that is not involved in determining the sex of an organism. ex. humans have 22 autosomes in a human cell.

Centromere

The region where two sister chromatids are held together in a chromosome.

Chromosome

A structure in the nucleus that contains DNA

Crossing over

The exchange of chromosomal segments between a pair of homozygous chromosomes.

Gamete

A male or female reproductive cell

Haploid

-A cell that contains only one set of chromosomes and the same sequence of genes as another chromosome

-Produced in meiosis

-Half the number of chromosomes found in the nucleus

Diploid

-Two sets of chromosomes

-Double the number of chromosomes found in the nucleus

-non-sex cells

A

Adenine

T

Thymine

G

Guanine

C

Cytosine

Karyotype

A photograph of pairs of homologous chromosomes in a cell

Sister Chromatids

one of two chromosomes that are genetically identical and held together in a chromosome

Nondisjunction

The failure of homologous chromosome pairs or sister chromatids to separate during meiosis

Type A blood

- Can accept A because it has A antigens

- Can accept O blood because there are no antigens

- Can't accept B or AB blood because it has B antibodies

Type B blood

- Can accept B because it has B antigens

- Can accept O blood because there are no antigens

- Can't accept A or AB blood because it has A antibodies

Type O blood

- Can accept O because it has no antigens

- Can't accept A, B, and AB because it makes A and B antibodies

Type AB blood

- Can accept AB because it has AB antigens

- Can accept O because it has no antigens

- Can accept A and B because of no antibodies

Genetics

The study of heredity and variation

Homologous Chromosomes

Carry information for the same genes and are similar in size and shape

Monosomy

a daughter cell is missing a chromosome (non-disjunction

Trisomy

a daughter cell has an extra chromosome (non-disjunction)