Genetics Basics Notes/Discussion

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Learning Goals:#s 1-6

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Reproduction- Review All cells come from pre-existing cells. Cells pass on their information to the

next generation of cells by mitosis. Asexual reproduction involves only one

source of genetic information (parent). Sexual reproduction involves two

parents.

Consider these questions: WHY do you look different than the

other humans in this room? What are some examples of inherited

variations? How does this happen? Where do they

come from?

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Genetics- An Introduction

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Genes and Chromosomes All genetic material is made up of the

chemical DNA (Deoxyribonucleic Acid)

It is found in all organisms and only differs in the order of the bases, but contains the same 4 bases: A, T, C & G

Sections of DNA that serve as a “recipe for proteins” are called genes

All of the DNA in the human cell is divided into 46 large pieces called chromosomesDNA

wrapped around

proteins

coiled up

chromosome

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Genes and Chromosomes Humans have about 25,000 genes on 46 chromosomes

that make up our genome (all the DNA for an organism)

Fun Fact:About 98% of the

DNA on our chromosomesdoes not seem to

code for any proteins- Genes make up only 2%!

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Karyotype Photos of chromosomes are arranged into matched & ordered pairs

10Genetics 101: What are Genes?

What is Genetics? Heredity is the passing of traits from

parents to offspring Genetics is the study of heredity

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A note about families... it’s not all genetic!

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... or easily explained!

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“Blended” Families

15“Mini-Me?” 16

Genetics Basics Definitions Each individual has two copies of each

gene (one from each parent). There are different forms of a gene which

are called alleles.

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Dominant alleles are: expressed and cover up recessive alleles written with a capital letter (“T”) eg. TT and Tt would both be tall.

Recessive alleles are: only expressed if two of them are present represented by a lower case letter (“t”) eg. an organism with tt is short