HEREDITY AND REPRODUCTION

GENETICS Genetics is the study of heredity, or the passing of traits from parents to offspring. Traits are the physical characteristics organisms exhibit. Genes are sets of genetic information in your body which control what type of trait you will exhibit. Chromosomes are parts of the cell which contain genetic information (DNA).

ASEXUAL REPRODUCTION Only 1 parent. Offspring is an exact copy of the parent. More common in single celled organisms such as bacteria, but can occur in plants and animals.

WAYS ASEXUAL REPRODUCTION OCCURS Single celled organisms. Mitosis-a process of cell division which forms two new cells, each having the same number of chromosomes. Binary fusion-a cell splits into 2 identical cells. (same as mitosis except with simpler organisms)

Multi-celled organisms Budding-organism produces tiny offspring on its side which grow off. Vegetative reproduction-tiny plants grow off full grown plants.

STOP!! In your own words, define asexual reproduction immediately on your paper!!!! Or else!

THINK, PAIR, SHARE… Think silently what some advantages of asexual reproduction are. Discuss these advantages with your partner next to you. Share your findings with the class!

ADVANTAGES OF ASEXUAL REPRODUCTION Much faster, fast population increase. Genetic continuity (offspring are identical to parents). Limits the spread of negative traits (only organisms with those bad traits will pass them down).

DISADVANTAGES OF ASEXUAL REPRODUCTION If the environment changes, there are no variations, so the whole population may become extinct. If a mutation occurs creating a bad trait, all individuals will inherit the mutation.

SEXUAL REPRODUCTION Two parents. Half the genes come from the mother while the other half come from the father. Offspring genetically different.

Special cells called gametes join together in a process known as fertilization. The sperm and egg cells both have half the number of chromosomes. Gametes are created through a process called Meiosis.

STOP!! In your own words, describe sexual reproduction on your paper right now!!

BRAINSTORM. In your lab table, come up with some advantages of sexual reproduction! Take a minute! Be active learners!

ADVANTAGES OF SEXUAL REPRODUCTION Variations in species-new combinations of traits increase organisms chances for survival. If an environment changes, the entire population will not become extinct (those with good traits will survive) Competition for females allow only the males with the best traits to reproduce.

DISADVANTAGES OF SEXUAL REPRODUCTION Takes time. Bad traits can be easily passed along.

CLONING Artificial asexual reproduction. A body cell is taken from an organism and the nucleus is removed. The nucleus is transplanted into an egg cell of the same organism. When the egg develops, it is a genetic clone of the original organism.

TYPES OF CLONING DNA cloning-only a small portion of an organisms DNA is copied and “pasted” into another organism. The new DNA begins to replicate. Reproductive cloning-making an exact copy of an organism. Sheep, pigs, cows, cats and rabbits. Embryo cloning-cloning the human embryo to harvest and study stem cells.

CREATION OF GAMETES Meiosis (Not MITOSIS!!) Only occurs in the formation of gametes. One cell splits into four cells, each with half the number of chromosomes as the parent cell. Genes are randomly distributed between the four cells.