Cell Division Mitosis & Meiosis

Mitosis The form of cell division by which a eukaryotic somatic cell (body cell) duplicates. Mitosis is asexual reproduction. Cell division is the continuation of life based on the reproduction of cells.

Mitosis each human body cell has 46 chromosomes two identical daughter cells Liver Cell 46 chromosomes Liver Cell (Parent cell)

A chromosome is a very long, continuous piece of DNA. What Is A Chromosome? A chromosome is a very long, continuous piece of DNA. Chromosomes contain many genes. Genes are the units of heredity in organisms. DNA double helix chromosome

Meiosis Meiosis is the process of cell division that only occurs in gametes or sex cells(egg & sperm). During meiosis, a cell produces 4 gametes with half the number of chromosomes in each gamete. The traits are distributed randomly in the newly formed gametes.

Number of Chromosomes in some Species of Animals # Fruit fly 8 Guinea Pig 16 Dove Snail 24 Earthworm 36 Tibetan fox Cat 38 Pig Mouse 40 Rat 42 Rabbit 44 Syrian hamster Hare 46 Human Gorilla 48 Sheep 54 Elephant 56 Cow 60 Donkey 62 Horse 64 Dog 78 Chicken Carp 104 Butterflies 380

23 pairs (46) of chromosomes in human Female Male

Why Do I Look Like My Parents??? Genes & Heredity Why Do I Look Like My Parents???

Question: Why Don’t You Look Like a rhinoceros?

Answer: Because _______. Heredity is the passing of traits from parents to offspring. Traits and characteristics pass from parents to offspring through genes.

Genetics Terms Alleles: the different forms of a gene. Dominant allele: an allele whose trait always shows up when it is present. Recessive allele: an allele that is masked when a dominant allele is present.

Homozygous vs. Heterozygous If both the alleles inherited by the zygote(fertilized egg) for a particular characteristic are the same they are called homozygous. If they are different from each other they are called heterozygous.

Homologous Chromosomes? What the … Each set of chromosome is a homologous pair Homologous chromosomes – chromosomes which contain the same genes, one from each parent Homologous chromosomes look alike with similar information stored on them One member of each homologous pair is inherited from each parent through egg or sperm.

Homologous Chromosomes =(Location)

Dominant Allele vs. Recessive Allele

Genotype & Phenotype A set of alleles inherited by an individual is called a genotype. The way the genes express themselves in the individual's appearance is their phenotype.

Dominant & Recessive Traits Some traits show more often than other traits. The traits that show often are called dominant traits. Those traits that don’t show often are recessive traits.

Both mother and father are heterozygous for tongue rolling. Genotype & Phenotype Both mother and father are heterozygous for tongue rolling. Genotype: heterozygous alleles (one dominant & one recessive) Phenotype: Ability to roll tongue

Albino snake, a recessive trait of not having colors

Attached earlobe vs. free Attached is a recessive trait (or detached) earlobe Attached is a recessive trait

Some Dominant Traits Curly Hair Dark Hair Mid-finger Hair Widow’s Peak Tongue Rolling Widow’s Peak Black Eyes Some Dominant Traits

Punnett square Punnett Squares are diagrams used to help us to figure out how inherited traits (characteristics) will be distributed Dominant trait is written by capital letter (A) Recessive trait is written by lower case letter (a)

Punnett square Both parents birds are homozygous, with the red bird having 2 dominant alleles, and the blue bird having 2 recessive alleles. There is only one possible genotype for all the offspring, and that is heterozygous. What is the phenotype of the offspring? ______

Practice with Punnett Square In rabbits, black fur is dominant to white fur. A male rabbit with BB genotype and a female with a Bb genotype are crossed. What is their phenotype? What are the possible genotypes and phenotypes of the offspring? (Show using a Punnett square) What is the percent chance for each type?

Questions- page 19L Copy & answer What is heredity? What is genetics? Who was Gregor Mendel? What type of organism did he work on? What does true-breed mean? What does self-pollinate mean? What is offspring? In genetics, what is P, F1, F2? What does cross-pollination mean? Define dominant & recessive.

Inside the nucleus of a cell long strings of DNA are coiled up and spooled onto chromosomes, and on each chromosome there are several thousand genes - shorter sections of DNA which act as a code for a particular characteristic. Since we inherit particular chromosomes through the egg and sperm, we also inherit the particular characteristics coded for by the genes on those chromosomes.