Biology Chapter 7.1Inheritance of Traits

Pages 134-140

Inheritance Terms• life cycle

• A description of the growth and reproduction of an individual.

• Egg cell and sperm cell (gametes) are produced by meiosis.

• Egg and sperm fuse at fertilization to create a zygote.

• Then this zygote copies all of the genetic information it contains then goes through mitosis to make two identical daughter cells.

• Each daughter cell divides many times producing an embryo.

Inheritance Terms

• Division of the embryo continues leading to the production of a full term infant and eventually an adult.

Chromsome Number

Prokaryotes

• 1 circular chromosome in each cell

Eukaryotes

• more than 1 linear chromosome in each cell

Variation in Chromosome Number

Organism (Eukaryotes)

Chromosome Number (in each cell)

jumper ant 2

stalked adder's tongue

1260(in picture)

human 46

Instruction Manual

• Genes as words in an instruction manual. Different words from the manual are used in different parts of the body, and identical words may be used in distinctive combinations in different cells.

Gene Mutation creates Genetic Diversity

• Mutations in genes lead to different versions, or alleles, of the gene.

• Mutations are random.

Nucleotide Mutations

Codon Table

Mutation Worksheet

Inheritance

• Each parent gives a complete set of instructions to each offspring.

Large variety of offspring

segregation:

• the separation of pairs of alleles during the production of gametes.

independent assortment:

• Alleles for each gene are inherited independently of each other.

• Arises from the random alignment of chromosomes during meiosis.

random fertilization:

• gametes combine without regard to the alleles they carry

Identical Twins• Identical twins are

monozygotic twins.

• They develop from a single egg and sperm.

• Monozygotic twinning occurs when cells in an embryo separate from each other.

• If this happens early in development, each cell or clump of cells can develop into a complete individual, creating genetically identical twins.

• One in every 285 pregnancies results in identical twins.

Fraternal Twins

• Non identical twins or fraternal twins are dizygotic.

• They occur when two separate eggs fuse with different sperm.

• Embryos that develop are genetically different.

• 1 in every 80 pregnancies results in fraternal twins.