Chapter 3 - Heredity
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DNA Full Name
Deoxyribonucleic Acid.
DNA Does
Makes proteins that are responsible for producing physical traits. i.e eye colour.
Gene
Segment of DNA that codes a specific protein.
Gene Process
Step 1. The gene transcribes into a molecule called RNA. Step 2. The RNA carries the genes sequence to a cell structure called a ribosome - where a protein is built.
RNA
Ribonucleic Acid
Dogma
DNA to RNA to Protein is so specfic and key in living things that its reffered to as the Central Dogma of Biology/Molecular Biology.
Chromosomes
Reproductive cells contain DNA in the form of structures called Chromosomes.
Chromosomes in Normal Body Cells
46 Chromosomes each.
Chromosomes in Reproductive Cells
23 Chromosomes each.
Chromosomes Stored
Chromosomes that store DNA are located in the cells nucleus.
Chromosomes Breakdown
A chromosome consists of two identical chromatids attached at the centromere. Hundreds/thousands of genes can be stored on once chromosome.
Alleles
Different versions of a gene. Most genes have 2 alleles, more are possible. i.e eye colour (Blue/Brown), blood type (A,B & O).
Mutations
New Alleles for a gene. Mutation is a random change in the base sequence of a gene.
Mutation Types
Single Base Change, Additions & Deletions.
Crossing Over
Before chromosomes are separated, they go through s process called crossing over. An arm from each chromosome literally “crosses over” the other, allowing the arms to trade segments.
Enviromental Altering of Traits
Some traits are a result of a combination of alleles and environmental factors.
Enviromental Factors
Height - Poor diet can limit how tall one can grow/stunt ones growth. Handedness - Injury to dominant hand can require one to learn to use the other. Cancer - Lifestyle choices can increase ones risk. E.g smoking/drinking/diet etc.
Expression of Traits
When a gene is actively used to make a protein it is said to be turned on or expressed. Some genes are expressed all the time. Others only when a specific protein is needed.
Epigenetics
The study of how genes are turned on and off.
Enviromental Epigenetics
Environmental factors can determine which genes are expressed. E.g Temperature.
Inheritance
You have two copies of every gene. One from each parent.
Genotype
Your combination of alleles for a specific gene.
Phenotype
Physical appearance for a trait. Determined by your genotype.
Simple Inheritance
Gene has one dominant allele and one recessive allele.