Warm-Up #7

▪What were the conditions necessary for life to evolve on Earth?

Warm-Up #7

▪1) Essential chemicals▪2) Source of Energy▪3) Liquid Water▪4) Lots of time!

So how did we go from this?

To this?

Evolution!

Evolution

▪Evolution:▪Is the slow process that brings about changes in

populations of living things

▪It occurs randomly and selectively

▪Randomly: genes will mutate at random causing changes in individuals

▪Selectively: through natural selection these changes might be transmitted to further generations

Evolution

▪Natural selection:▪Occurs at the individual level; acts on individual organisms

▪Leads to evolution

▪Evolution:▪Occurs at the species or population level

Individuals cannot evolve; species evolve

Sexual Selection

Types of Selection

▪Natural selection:▪differential survival and reproduction of individuals due to differences in phenotype (the way they look)

Types of Selection

▪Sexual selection:▪is a mode of natural selection where members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex (intrasexual selection)

Types of Selection

▪Artificial selection:▪The process by which humans breed animals or plants to selectively develop particular traits

Genetic Information

▪The whole process of selection and evolution is highly dependent on cellular reproduction and passing on of genetic material

What is genetic material?

What do you know about:- DNA?- Genes?- Chromosomes?

DNA

•DNA stands for Deoxyribonucleic Acid

•DNA is the hereditary material of most organisms:• It contains the “code” that will program the different

processes that are required for building and maintaining an organism

•Reading the code tells the cells and its structures what to do

DNA

•A DNA molecule is a double helix structure (a twisted ladder)

Each “bar” in the ladder is called a nucleotide and is made of 2 base pairs.

You’ll learn more about this next year!

A complete molecule of DNA is called a chromosome.

Chromosomes and Genes

▪Chromosomes: ▪Structures containing an individual’s genetic code (a complete molecule of DNA). In animal and plant cells, the chromosomes are located in the nucleus.

▪Chromosomes form when DNA packs itself up tightly by coiling itself again and again until it is shaped like an X.

Chromosomes and Genes

Chromosomes contain:

▪Genes: ▪These are chromosome segments that determine specific genetic characteristics.

▪ex: eye color, skin color, etc.

Chromosomes and Genes

We all have similar genes but minor differences make us all unique.

▪There are different variations of genes possible and these can be dominant or recessive.