1. dna 2. gene 4. genome 5. individual 3. chromosome 7. population 6. family (pedigree) cell human...

1. DNA2. Gene

4. Genome

5. Individual

3. Chromosome7. Population

6. Family (pedigree)

Cell

Human Genetics

A karyotype is a set of photographs of chromosomes grouped in ordered pairs.

Human Chromosomes• We get 23 pairs of chromosomes.

• One set from our mom, and one set from our dad, for a total of

46 chromosomes.

Sex Chromosomes• The first 44 chromosomes are

known as autosomes.

• The last 2 are called sex chromosomes because they determine an individual’s sex.

• Females are XX.• Males are XY.

What is the probability that a newborn will be male or female?

XX XX

XY XY

Female (XX) X X

XMale (XY)

Y

1 2

A pedigree is a chart that shows the relationships within a family.

Circle = femaleSquare = male

Horizontal line connecting a male and female = marriage

Vertical line and a bracket connect the parents to their children

Half-shaded circle or square = person is a carrier of the trait

Completely shaded circle or square = person expresses the trait.

Circle or square that is not shaded = person neither expresses the trait nor is a carrier of the trait.

Section 14-1

Figure 14-3 A PedigreeUnderstanding a Pedigree

Insert 10-15 on study guide.

Homologous chromosomes fail to separate

Meiosis I:Nondisjunction

Meiosis II

Section 14-2

NondisjunctionNondisjunction

Nondisjunction is an error in meiosis in which chromosomes fail to separate

Chromosomal Disorders• Monosomy occurs when one

chromosome from a pair is missing.

• Trisomy occurs when there is an extra, or third, chromosome for one pair.

Trisomy 21(Down’s Syndrome)

Trisomy XXY(Klinefelter’s Syndrome)