Biology Chapter 11 Genetics Study Guide

Genetics
The study of heredity
Who is known as the father of genetics?
Gregor Mendel
What did Mendel work with in his experiments of genetics?
Garden peas
Why did Mendel pick pea plants to use in his experiments?
This was because these plants reproduce
What does the male part of the pea plant contain?
This part contains the pollen
What does the female part of the pea plant contain?
This part consists of the egg cells
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In order to perform his experiments, what did Mendel have to do?
Mendel selected the pea plants he would mate with each other. He then cut the male parts of the flower off and dusted them with pollen from a second flower
Trait
A trait is a specific characteristic that varies from one individual to another
What did Mendel do when he crossed the plants?
Mendel crossed plants with each of the 7 contrasting characters and studied their offspring (homozygous)
Hybrid
The offspring of crosses between parents with different traits (heterozygous)
What conclusions did Mendel come up with after his experiments?
Mendel found that biological inheritance is determined by factors that are passed on from one generation to the next
Probability
The likelihood that a particular event will occur
Why are the principles of probability important to genetics?
They can be used to predict the outcomes of genetic crossings
Punnet Squares
Are used in genetics to help determine what gene combinations might result from a genetic cross
What letters represent dominant alleles?
Capital letters
What letters represent recessive alleles?
Lowercase letters
Homozygous
Two identical alleles for a particular trait
What is an example of homozygous?
TT, tt
Heterozygous
Two different alleles for the same trait
Phenotype
Physical characteristics
Genotype
Genetic makeup
Monohybrid
One trait is crossed at a time
Dihybrid
Two traits are crossed at a time
Law of Dominance
The inheritance of biological characteristics is determined by individual units known as genes. In organisms that reproduce sexually, genes are passed from parent to their own offspring
Law of Segregation
In most sexually reproducing organisms, each adult has 2 copies of each gene, one from each parent. These genes are usually segregated from each other when gametes are formed
Law of Independent Assortment
The alleles for different genes usually segregate separately of one another
Incomplete Dominance
Cases in which one allele is not completely dominant over another
What is the intermediate phenotype in incomplete dominance?
This is the phenotype somewhere in between the 2 main phenotypes
Homologous Chromosomes
Are chromosomes that each have a corresponding chromosome from the opposite sex parent
Diploid
Means two sets and is used to describe both sets of homologous chromosomes
Haploid
When there is only a single set of chromosomes
Meiosis
The process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell
What two states does meiosis have?
PMAT I and PMAT II
Tetrad
A structure formed when each chromosome pairs with its corresponding homologous chromosome
Crossing Over
A process by which homologous chromosomes can also exchange parts of their chromatids
What does meiosis 1 result in?
This results in two haploid daughter cells, each with 1/2 the number of chromosomes as the original cell
What does meiosis II result in?
This results in 4 haploid daughter cells
What does meiosis create?
Meiosis creates gametes with half the number of body cells
Why is Thomas Hunt Morgan important to genetic studies?
His research with fruit flies led to “Principle of Linkage”
Principle of Linkage
When many genes appear to be linked
Gene Linkage
Genes located on same chromosomes are genetically inherited together
How does gene linkage affect the usual ratios found when working punnet squares?
They can alter usual ratios
What is a gene map?
Diagram showing relative locations of genes on chromosomes
How are the locations of genes determined on a gene map?
Look at the rate at which genes were separated and recombined to figure out the distances between genes