Download Topic 4: Wearing Your Genes Continuous vs. Discrete Variation

Topic 4: Wearing Your Genes
Continuous vs. Discrete Variation: ​
Continuous variation is when there are a RANGE of
possibilities for each trait (hair color, skin color, height)
Discrete variation is when there are limited amount of possibilities for each trait (blood type, sex
etc.)
Nature vs. Nurture Debate (study of identical twins): ​
This is the ongoing debate about whether
you are who you are due to genetics (nature) or your environment (nurture).
Dominant vs. Recessive Traits: ​
Dominant trait: an inherited trait that shows up in the offspring.
Recessive an inherited trait that shows up in the offspring only if both parents passed on the
genes for the trait; when mixed with genes for a dominant trait, a recessive trait does not show
up in the offspring.
Mutations: ​
Mutations are changes in the DNA, the genetic material. These are caused by
mutagens. Most often mutations do not have any effect on the organism (usually that cell dies),
but there are times when the mutation can be harmful (cancer) or helpful (Sickle cells). The only
time mutations become passed on is when the mutation occurs in the gametes (the reproductive
cells).
Topic 5: When Plans Change
Mitosis (Occurs where? Results in how many cells? What happens to the # of chromosomes?):
Somatic cells (body cells) divides in a process called Mitosis where the daughter cells (diploid)
are identical (clones) of the parent cell.
Meiosis (Occurs where? Results in how many cells? What happens to the # of chromosomes?)
Gametes are created by a process called Meiosis. This begins the same way as the division of
somatic cells. Prior to cell division, each chromosome is copied. Cell division occurs 2 times. The
final result is that the gametes have HALF the original number of chromosomes (haploid).
Gene (definition): ​
A section in the DNA that codes for a specific protein.
Chromosomes (What is the definition? How many in body cells? How many in sex cells?)
Composed of strands of DNA are contained in a cell’s nucleus. Human somatic cells have 23 pairs
of chromosomes (46). People who have Down Syndrome (Trisomy 23) have one extra
chromosome. In gametes there are only 23 chromosomes.
Structure of DNA: ​
DNA is made up of a nucleotide which is a sugar, phosphate and a nitrogen
base. There are 4 types of nitrogen bases: Adenine, Cytosine, Guanine and Thymine. Because
DNA is a double helix, nucleotides join in pairs where Adenine goes with Thymine, and Cytosine
pairs with Guanine.
Technology in Genetics : Biotechnology, Genetic Engineering, Hybrids
Biotechnology is the scientific technologies associated with biology. One example is genetic
engineering in which scientists move genes from one organism to another. One example is how
bacteria are inserted with the gene to create human insulin. The waste product of the bacteria
contains the insulin, which is then given to humans who are diabetic. Genetically modified, or
transgenic, animals are produced when human genes are added to the fertilized egg of an animal.
Topic 6: The Best Selection
Artificial Selection: ​
a Technique in which individual plants or animals with desirable traits are
bred together to develop plants or animals with specific traits; also called selective breeding.
Selective Breeding ​
See above
Process & Outcome of Natural Selection: ​
The “strongest” will survive. Meaning, the organism
with the specific traits that are ideal for survival will live to pass on it’s genetic material. The
traits that allowed it to survive will be passed on to the offspring and the cycle continues until we
get a new species. If an organism doesn’t have ideal traits it won’t live or won’t be able to
reproduce to pass on it’s undesirable traits.
Theory of Natural Selection:
1. All organisms produce more offspring than can possibly survive.
2. There is incredible variation within each species.
3. Some of these variations increase the chances of an organism surviving or reproducing.
4. Over time, variations that are passed on lead to changes in the genetic characteristics of a
species.
Darwin's Finches & Light/Dark Moths (How are these examples?): ​
Through SPECIATION, it is
believed that the Darwin finches came from one ancestral species and through time and
competition the finches moved into various species due to beak shape (amongst other factors).
Read pg. 65 “Did you know” about the peppered moth.
Galapagos Islands and Darwin: ​
It is here where Darwin developed a theory of natural selection to
explain how a process closely related to natural selection occurred in nature.