Chapter 6 Mendel and Meiosis

What are homologous chromosomes?

Same length, same genes, and same centromeres

After meiosis, how many total chromosomes are in a human cell

23 (sperm + egg)

What does diploid mean?

double - 46

What does haploid mean?

half - 23

Examples of diploid and haploid

D - all body cells
H - sperm + egg

What is the law of segregation?

Same genes will segregate during gamete formation

What is the law of independent assortment?

In metaphase, the position of one chromosome does not impact the position of another

What is a monohybrid cross?

Aa + Aa

What is a dihybrid cross?

AaBb + AaBb

What is the other parent’s genotype?

Aa

What is the difference between homozygous and heterozygous?

Homozygous - Two of the same - AA / aa
Heterozygous - Two different - Aa

Why might a recessive allele not be physically expressed?

It may be masked by a dominant allele

What event(s) in meiosis increase genetic variety in offspring?

Crossing over

What types of chromosomes participate in crossing over?

Homologous chromosomes

To show a recessive disorder, the person must be what?

Homozygous recessive

Why do males present with sex-linked disorders at a higher rate?

Males have only one X chromosome, so a single recessive allele on that chromosome will result in the disorder

What tool is used to match chromosome pairs?

Karyotype

What is a family record that shows a trait?

Pedigree

How can a female express a recessive sex-linked trait?

Must be homozygous

What are autosomes?

One of the numbered chromosomes

What are sexchromosomes?

X and Y

What do shaded shapes mean?

They have the trait

What genotype is a carrier?

Aa