Chapter 6, Section 1 Human Inheritance

Patterns of Human Inheritance The traits you get from both your mother’s side of the family and your father’s side a single gene with one dominant and one recessive allele, for example, widow’s peak These traits have two different phenotypes (physical appearances) Inheritance Some human traits are controlled by: See Brain Pop – “Heredity” A - dominant allele for widow’s peak a - recessive allele for straight hairline Both parents are heterozygous for widow’s peak (Aa)

Other human traits are controlled by: Single genes with multiple alleles For example, blood has 3 alleles: i, IA, and IB It’s the combination of these alleles that determines your blood type

The genes act together as a group to produce a single trait Many genes For example, height, skin, and hair color The genes act together as a group to produce a single trait Finally, other human traits are controlled by:

Table Talk: (Summarize) What are the three patterns of inheritance that control human traits? 1. A single gene with one dominant and one recessive allele 2. Single genes with multiple alleles 3. Many genes

Sex Chromosomes One of the 23 pairs of chromosomes in each body They determine whether a person is male (XY) or female (XX) They also carry genes that determine other traits (for example, color blindness is more common in males) See Brain Pop “Gender Determination”

a picture of all the chromosomes in a cell Karyotype a picture of all the chromosomes in a cell used to diagnose genetic disorders, such as Down syndrome TABLE TALK: Is this the karyotype of a male or female?

Quick Write: What is the difference between genotype, phenotype and karyotype?

Genes and the environment Many of an organism’s characteristics are determined by an interaction between both Examples: diet can affect height; opportunities to play sports can affect athletic ability

Selective Breeding The process of selecting organisms with desired traits to be the parents of the next generation TABLE TALK: Do you think people should have the ability to genetically choose what their children should look like? Explain See Discovery Education video, “Biologically Speaking – Genetics & Heredity” 16 min. end