CHPT 13 MEIOSIS AND SEXUAL LIFE CYCLE

The transmission of traits from one generation to the next is called

Inheritance

The study of heredity and variation is known as

Genetics

Genes are made up of

DNA

Genes are passed to offspring through

Gametes

A gene’s specific location on a chromosome is called its

Locus

In asexual reproduction, an individual passes genes to offspring

Without fusion of gametes

A clone is

A genetically identical group of offspring

Sexual reproduction results in offspring that are

Genetically unique

The term for the full sequence of stages in an organism’s reproductive history is

Life cycle

A karyotype shows

All pairs of chromosomes from a cell

Homologous chromosomes

Have the same length and centromere position

Which chromosomes determine the sex of an organism?

Sex chromosomes

Females have which pair of sex chromosomes?

XX

Males have which pair of sex chromosomes?

XY

How many autosomal pairs are in humans?

22

Fertilization is the union of

A sperm and an egg

A fertilized egg is called a

Zygote

The zygote undergoes which process for growth and development?

Mitosis

Ovaries and testes produce

Haploid gametes

Meiosis produces

Four genetically different gametes

How many rounds of division occur in meiosis?

Two

DNA replication occurs

Before Meiosis I only

During Meiosis I Prophase I, what major event occurs?

Chromosomes pair and crossing over occurs

What are chiasmata?

Sites of crossing over

During Meiosis I Metaphase I, chromosomes

Line up in homologous pairs

During Meiosis I Anaphase I

Homologous chromosomes separate

At the end of Meiosis II, how many chromosomes are in each human gamete?

23

What structure holds homologs together tightly?

Synaptonemal complex

What is synapsis?

The pairing of homologous chromosomes

Crossing over produces

Recombinant chromosomes

Which of the following contributes to genetic variation?

All of the above

Independent assortment refers to

Random alignment of homologous pairs

How many possible chromosome combinations can result from independent assortment in humans (n = 23)?

2²³ (~8 million)

Random fertilization increases variation because

Any sperm can fertilize any egg

The fusion of gametes with 8.4 million combinations each can produce a zygote with how many diploid combinations?

70 trillion