Chapter 17 Section 1: Genetic Variation

Chapter 17 Section 1: Genetic Variation

Section 2 Content Objective Write this down! I will be able to identify and define in my own words key terms associated with genetic variation.

Section 2 Language Objective Write these down! I will be create a vocabulary graphic organizer on key terms associated with Genetic Variation. For each term I will record the word, define it in my own words, use it correctly in a sentence, and create a mnemonic that will help me remember each word and its meaning.

Chapter 17 Section 1: Genetic Variation Key Vocabulary Terms 9

Population genetics The study of the frequency and interaction of alleles and genes in populations

1. A distribution of numerical data whose graph forms a bellshaped curve that is symmetrical about the mean. 2. A line graph showing the general trends in a set of data of which most values are near the mean (average). Normal Distribution

Polygenic A character that is influenced by several genes

An overview of the relative frequency and range of a set of values. Mathematically, a distribution is a tally or a histogram with a smooth line to show the overall pattern of the values. Distribution

Bell curve A symmetrical frequency curve

Gene pool The particular combination of alleles in a population at any one point in time.

Mean (Average) The number obtained by adding up the data for a given characteristic and dividing this sum by the number of individuals

Median The Median is the "middle number" (in a sorted list of numbers).

Mode The value that occurs most frequently in a data set or a probability distribution.

Chapter 17 Section 1: Genetic Variation Supplementary Words

Deduce Arrive at (a fact or a conclusion) by reasoning; draw as a logical conclusion.

Frequency The proportion or ratio of a group that is of one type.

Generate Produce; bring into being; cause to be

Content Objectives I will be able to identify: How microevolution is studied How phenotypic variation is measured How genetic variation and change are measured How genetic variation originates

Language Objectives Write This down! 1. I will create and complete Cornell Notes on information presented on Genetic Variation 2. I will read aloud with my small group a small article on Genetic Variation, discuss its content, and collaboratively complete questions on its content. (Active Reading)

Chapter 17 Section 1: Genetic Variation Notes

Chapter 17 Section 1: Genetic Variation Population Genetics

Population Genetics Charles Darwin knew that heredity influences characteristics, but he did know about genes.

Population Genetics We can now study and predict genetic variation and change that underlie evolution.

Population Genetics Microevolution is evolution at the level of genetic change in populations.

YOUR TURN Active Reading Section 1 Genetic Variation

Population Genetics, continued Microevolution can be studied by observing changes in the numbers and types of alleles in populations, called population genetics.

The study of genetics and evolution are advancing together.

The fields of ecology, genetics, and evolutionary theory are brought together to understand how genetic changes in populations result in changes to species over time

Population Genetics, continued The link from microevolution to macroevolution speciation can be studied in detail.

Chapter 17 Section 1: Genetic Variation Phenotypic Variation

Think, Share, Write #1 What do we now know about heredity that Darwin did not know?

Think, Share, Write #1 What do we now know about heredity that Darwin did not know? We now know about genetics, such as how genotype relates to phenotype.

Phenotypic Variation The variety of phenotypes that exists for a given characteristic depend on how many genes affect it.

Phenotypic Variation Polygenic characters are influenced by several genes. Examples include human eye color, skin color, and height.

Biologists study polygenic phenotypes by measuring each individual in the population and then analyzing the distribution of the measurements.

Phenotypic Variation, continued A distribution is an overview of the relative frequency and range of a set of values.

Often, some values in a range are more common than others.

Phenotypic Variation, continued A normal distribution, or bell curve, is one that tends to cluster around an average value in the center of the range.

Normal Distribution

Think, Share, Write #2 Why do polygenic characters vary so much?

Think, Share, Write #2 Why do polygenic characters vary so much? Polygenic characters vary so much because many unique combinations of alleles are possible.

Measuring Variation and Change The particular combination of alleles in a population at any one point in time makes up a gene pool.

Measuring Variation and Change Genetic variation and change are measured in terms of the frequency of alleles in the gene pool of a population.

Genotype Frequencies Vs. Allele Frequencies

A frequency is the proportion or ratio of a group that is of one type. To study genetic change, the frequency of each allele in a population can be tracked over time.

Sources of Genetic Variation Evolution cannot proceed if there is no variation. The major source of new alleles in natural populations is mutation in germ cells.

Think, Share, Write #3 What is the main measure of genetic variation?

Think, Share, Write #3 What is the main measure of genetic variation? The main measure of genetic variation is frequency of alleles.

Sources of Genetic Variation Mutation generates new alleles at a slow rate. Only mutations in germ cells (egg and sperm) are passed on to offspring.

Summary Microevolution can be studied by observing changes in the numbers and types of alleles in populations.

Biologists study polygenic phenotypes by measuring each individual in the population and then analyzing the distribution of the measurements.

Summary Genetic variation and change are measured in terms of the frequency of alleles in the gene pool of a population.

Summary The major source of new alleles in natural populations is mutation in germ cells.