Science Lesson 26: Genes and Natural Selection

Animal and Plant

Organisms composed of only one cell are unicellular. Organisms composed of more than one cell are multicellular.

Prokaryotic Cells are simple cells without organelles. Eukaryotic cells are complex cells with organelles

Cell, Tissue, Organ, Organ System, Organism.

An austrian priest who worked with pea plants and their traits. He is often known as the father of Genetics.

The passing of physical characteristics from parent to offspring.

The scientific study of heredity.

Capital letter(T)

lowercase letter(t)

a type of molecule that carries the inherited information passed from parents to offspring. (shape is a twisted ladder)

a segment of DNA that contains the instructions for building a protein. A gene or group of genes control a trait.

a type of molecule that makes up much of our cells and therefore are body.

A chromosome is a long DNA molecule with the genetic material of an organism.

Traits are passed from parents to offspring through genes in DNA. (half of the DNA is from the egg, half from the sperm)

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The traits of an organism are determined by the kinds of proteins that its genes cause it to build.

Adenine to Thymine and Cytosine to Guanine.

A specific version or form of a gene

The mother has 2 alleles for each gene but she only gives a copy of one allele to her offspring. The father has 2 alleles for each gene but only gives a copy of one allele for each gene to his offspring. The offspring will then have 2 alleles for each gene.

Dominant alleles appear no matter what, but recessive alleles only appear when 2 recessive alleles are present.

phenotype- physical appearance of a genetic trait(Ex: Black hair or blue eyes) genotype- the allele combination of the trait (Ex: AA or Aa or aa)

A random change to an organism's DNA

Nucleotides provide the sequence for a specific amino acids. The amino acids connect to make a protein. Those proteins make up all the traits in our body.

Copy errors, environmental factors, small changes in the sequence of bases.

Mutations that affect the genes carried in an organism's eggs or sperm can be passed to the organism's offspring.

DDT resistant mosquitoes; a peppered moth with dark wings.

The genes are segments of DNA, which code for proteins, and those proteins make up our traits.

Before the industrial revolution, the peppered moths had light colored wings which allowed them to blend in to their background, which were light colored trees. During the industrial revolution the factories produced a lot of soot, covering the trees, and making the bark dark in color. The moths with dark colored wings thrived, because they easily blended into their surroundings. After the soot cleared up, the trees became light colored again and the light colored moths became the majority.

Natural selection is determined by how well a species is suited to their environment. The light colored moths were more suitable to their environment before the 19th century, because the trees were lighter in color, so the light colored moths were the majority. But during the industrial revolution, during the 19th century, when the air was polluted and the trees got covered in soot, the darker colored moths were more suited to their environment, because they could camouflage better,s o their population increased.

Natural selection helps determine what happens to a new allele once it enters the population. Depending on how the new allele affects the survival and reproduction of organisms, it could become more common in the population over time, or less common.

harmful- make organisms less likely to survive and reproduce in their environment neutral- do not affect an organism's probability of surviving and reproducing. beneficial- make organisms more likely to survive and reproduce in their environment.

harmful- cancer(cancer cells make copies of themselves which can threaten their chance of survival) neutral- attached versus free earlobes beneficial- lactase persistence(can digest lactose, a sugar found in milk)

is caused by a mutated version of the gene that helps make hemoglobin, a protein that carries oxygen in red blood cells. People with two copies of the sickle cell gene have the disease. People who carry only one copy of the sickle cell gene do not have the disease and are protected against malaria.

1. DNA opens like a zipper, inside the nucleus

2. mRNA is made with the matching bases(transcription

3. the mRNA strand travels out of the nucleus to a ribosome

4. mRNA is read by the ribosome(translation)

5. tRNA with the matching bases brings over the Amino Acids

6. The protein is made from the Amino Acids