Chapter 13 Memorization

What is a gene?

A segment of DNA that is a unit of heredity.

What is a locus?

A gene's specific location on a chromosome.

What is a chromosome?

A DNA-containing structure that carries genes.

What is a genome?

All of an organism's genetic material.

What is inheritance?

The passing of genes from parents to offspring.

What do offspring inherit from their parents?

Genes, not physical traits directly.

What is a gamete?

A reproductive cell, such as a sperm or egg.

What is the male gamete?

Sperm.

What is the female gamete?

Egg, also called an ovum.

What is a somatic cell?

Any body cell except gametes and their precursors.

How many chromosomes are in a normal human somatic cell?

46 chromosomes.

How many chromosome pairs are in a normal human somatic cell?

23 pairs.

How many chromosomes are in a normal human gamete?

23 chromosomes.

What is asexual reproduction?

One parent produces offspring without gamete fusion.

What is a clone?

Genetically identical individuals produced from one parent.

What is sexual reproduction?

Two parents produce offspring with unique gene combinations.

Which type of reproduction usually produces genetically identical offspring?

Asexual reproduction.

Which type of reproduction usually produces genetically varied offspring?

Sexual reproduction.

What is a life cycle?

The generation-to-generation reproductive history of an organism.

What is fertilization?

The union of sperm and egg.

What is a zygote?

A fertilized egg with chromosome sets from both parents.

What does diploid mean?

Having two sets of chromosomes.

What notation represents diploid?

2n.

What does haploid mean?

Having one set of chromosomes.

What notation represents haploid?

n.

What is the diploid number in humans?

46.

What is the haploid number in humans?

23.

What are homologous chromosomes?

A chromosome pair with the same genes at the same loci.

What is another name for homologous chromosomes?

Homologs.

Where does each homolog in a homologous pair come from?

One comes from each parent.

How are homologous chromosomes similar?

They are similar in length and shape.

What do homologous chromosomes have in common genetically?

They carry genes for the same inherited characters.

Can homologous chromosomes carry different alleles?

Yes.

What is an autosome?

Any chromosome that is not a sex chromosome.

How many pairs of autosomes do humans have?

22 pairs.

What are sex chromosomes?

Chromosomes that help determine biological sex.

What sex chromosomes do most human females have?

XX.

What sex chromosomes do most human males have?

XY.

What sex chromosome does a human egg carry?

X.

What sex chromosomes can a human sperm carry?

X or Y.

What is a karyotype?

An ordered display of chromosomes from a cell.

Why are somatic cells commonly used for karyotypes?

They contain both chromosome sets for examination.

What is a replicated chromosome?

One chromosome made of two sister chromatids.

What are sister chromatids?

Identical copies of one replicated chromosome.

What is a centromere?

The region where sister chromatids are attached.

What are nonsister chromatids?

Chromatids from different homologous chromosomes.

What happens to chromosome number after DNA replication?

It stays the same.

What happens to chromatid number after DNA replication?

It doubles.

A cell has 2n = 6 after DNA replication. How many chromosomes does it have?

6 chromosomes.

A cell has 2n = 6 after DNA replication. How many chromatids does it have?

12 chromatids.

What is the maternal chromosome set?

The chromosome set inherited from the mother.

What is the paternal chromosome set?

The chromosome set inherited from the father.

Where are sperm produced in animals?

In the testes.

Where are eggs produced in animals?

In the ovaries.

What process produces gametes?

Meiosis.

What is the main purpose of meiosis?

To reduce chromosome sets from diploid to haploid.

What kind of cell begins meiosis?

A diploid cell.

How many daughter cells result from meiosis?

Four haploid daughter cells.

When does DNA replication occur before meiosis?

During interphase before meiosis I.

How many divisions occur during meiosis?

Two.

What happens during meiosis I?

Homologous chromosomes separate.

What happens during meiosis II?

Sister chromatids separate.

How many divisions occur during mitosis?

One.

How many daughter cells does mitosis produce?

Two.

What happens to chromosome number during mitosis?

It is conserved.

How are mitosis daughter cells genetically related to the parent cell?

They are usually genetically identical.

How are meiosis daughter cells genetically related to one another?

They are genetically different.

What are the only haploid cells in the usual animal life cycle?

Gametes.

How are animal gametes produced?

By meiosis.

How does an animal zygote develop into an adult?

By mitosis.

What is alternation of generations?

A life cycle with multicellular haploid and diploid stages.

What is a sporophyte?

The diploid multicellular stage in plants.

What is a gametophyte?

The haploid multicellular stage in plants.

What is a plant spore?

A haploid cell made by meiosis in a sporophyte.

Is a sporophyte haploid or diploid?

Diploid.

Is a gametophyte haploid or diploid?

Haploid.

What does a sporophyte produce by meiosis?

Haploid spores.

What does a spore develop into by mitosis?

A gametophyte.

What does a gametophyte produce by mitosis?

Haploid gametes.

What does fertilization produce in a plant life cycle?

A diploid sporophyte stage.

What is usually the only diploid stage in most fungi and some protists?

The single-celled zygote.

What process does the fungal or protist zygote undergo?

Meiosis.

What is the usual ploidy of the adult stage in most fungi?

Haploid.

Can mitosis occur in haploid cells?

Yes.

Can mitosis occur in diploid cells?

Yes.

Can meiosis occur in haploid cells?

No.

Can meiosis occur in diploid cells?

Yes.

What happens during prophase I?

Homologs pair and crossing over occurs.

What is synapsis?

The pairing of homologous chromosomes in prophase I.

What is the synaptonemal complex?

A zipper-like structure that holds homologs together.

What are cohesins?

Proteins that hold sister chromatids together.

What is crossing over?

DNA exchange between nonsister chromatids of homologs.

What is a chiasma?

A visible crossover site between homologs.

What are chiasmata?

Multiple crossover sites.

What happens during metaphase I?

Homologous pairs line up at the metaphase plate.

What is a tetrad?

A paired set of duplicated homologous chromosomes.

What happens during anaphase I?

Homologous chromosomes separate.

What happens to sister chromatids during anaphase I?

They remain attached.

What happens during telophase I?

Haploid chromosome sets reach opposite sides of the cell.

What do daughter cells contain after meiosis I?

Haploid sets of duplicated chromosomes.