Science Lesson 26: Genes and Natural Selection

What are the two types of cells?

Animal and Plant

What is the difference between Unicellular and Multicellular?

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

What is the difference between Prokaryotic and Eukaryotic?

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

What are the levels of organization from Cell to Organisms?

Cell, Tissue, Organ, Organ System, Organism.

Who is Gregor Mendel?

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

What is heredity?

The passing of physical characteristics from parent to offspring.

What is genetics?

The scientific study of heredity.

How is a dominant allele represented?

Capital letter(T)

How is a recessive allele represented?

lowercase letter(t)

DNA

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

Gene

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

Protein

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

Chromosome

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

How do we get our traits?

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

How many chromosomes are in the human body?

46

How many chromosomes are in the human sperm/egg?

23

How does the sequence of our DNA create an organism?

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

Which nitrogen base pairs match up?

Adenine to Thymine and Cytosine to Guanine.

What is an Allele?

A specific version or form of a gene

How do we get our alleles?

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.

What is the difference between dominant and recessive alleles?

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

What is the difference between a phenotype and a genotype?

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)

What is a mutation?

A random change to an organism's DNA

How do nucleotides (sugar, phosphate and nitrogenous bases) provide a specific sequence that codes for a gene?

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.

What are the causes of mutations?

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

When are mutations passed to offspring?

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

What is an example of a mutation?

DDT resistant mosquitoes; a peppered moth with dark wings.

What is the connection between genes, proteins, and traits?

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

What happened to the peppered moths in England?

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.

How does the peppered moth show natural selection?

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.

How do mutations become more or less common in a population?

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.

What is the difference between harmful and beneficial and neutral mutations?

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.

Give an example of each of the three types of mutations.

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)

Explain the mutation of sickle cell anemia and describe how it affects the protein Hemoglobin.

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.

What are the steps of protein synthesis?

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