Chapter 9 study guide

1) Given a number of chromosomes at a specific phase in the cell cycle, be able to determine the number of chromosomes in a cell at any other phase of the cell cycle. For example: C) If a prophase 2 cell has 16 chromosomes, how many will each daughter cells contain?

16 chromosomes

1) Given a number of chromosomes at a specific phase in the cell cycle, be able to determine the number of chromosomes in a cell at any other phase of the cell cycle. For example: A) If a prophase cell has 16 chromosomes, how many will each daughter cell contain?

16 chromosomes (they are exact copies of the original)

Haploid is abbreviated as ___ because they have how many sets of chromosomes

1n because they have one set of chromosomes

Diploid is abbreviated as _____ because they have how many sets of chromosome?

2n because they have two sets of chromosomes

1) Know how many chromosomes a human cell would have if it were: A) 2n+1 B) 2n-1 C) 3n D) 1n

2n+1 = 47 2n-1 = 45 3n = 69 1n =23

1) Given a number of chromosomes at a specific phase in the cell cycle, be able to determine the number of chromosomes in a cell at any other phase of the cell cycle. For example: B) If a prophase 1 cell has 16 chromosomes, how many will each Prophase 2 cell contain?

8 chromosomes (it went through Anaphase I, meaning the chromosomes are cut in 1/2)

B) How are Anaphase, Anaphase 1 and Anaphase 2 alike and how are they different?

All anaphases' have sister chromatids separated to opposite poles - non-identical sister( anaphase 2) - identical sisters (anaphase 1)

1) Explain how nondisjunction can lead to Trisomy 21. Include the common name for Trisomy 21.

An extra copy of a chromosome (trisomy) causes genetic disorders such as Trisomy 21, or Down Syndrome

Which chromosomes are the Sex Chromosomes?

- 23rd pair of chromosomes- XX & XY (not numbered like the other 22)

What is the significance (or result) of crossing over?

- ONLY occurs in Meiosis I, Prophase I - 2 homologous chromosomes pair and exchange pieces of DNA, scrambling genetic material - Ensures you receive traits from both parents

What are the homologous chromosomes? How are these related to the "sets" of chromosomes?

- autosome pairs that are similar in structure in terms of genes and size - all normal autosomes in humans are homologous chromosomes

Which chromosomes are the Autosomes?

- the numbered chromosomes in a karyotype - all chromosomes except the 23rd (sex chrom.)

What is a karyotype and what sorts of information can you learn from a karyotype?

-Shows all 23 chromosomes from a diploid human cell- -Identify traits, diseases, & gender

There are two types of sex cells; the male sex cells are called _________ and female sex cells are called ________ and they are both formed by meiosis.

-XY -XX

The fusion of cells during fertilization forms a diploid cell called a ___________. This diploid cell will divide once by _________ to form a two-cell __________, which will continue to divide by _________ to eventually form the organism.

-zygote -mitosis -embryo -meiosis

Your haploid cells are __________ (somatic cells or gametes) and are formed by meiosis and are also known as sex cells.

Gametes

1) We defined "gene" in chapter 7. What then are alleles and how are they related to genes?

Genes: general descriptions of traits Alleles: specific descriptions of traits (type of gene)

Which sex chromosome combination results in female and which results in male?

Males have XY sex chromosomes while females have XX sex chromosomes; the male can contribute the X or Y chromosome, while the female must contribute one of their X chromosomes

A) Which looks more like mitosis, Meiosis 1 or Meiosis 2 and why?

Meiosis 2 - Both begin and end their processes with haploids - Similar Interphase, Prophase & Anaphase(except sister chromatids are NOT identical)

C) How many daughter cells are created by mitosis, how many by meiosis?

Mitosis - 2 genetically identical cells Meiosis - 4 genetically unique haploid cells

1) Define Polyploidy and Aneuploidy. Be able to recognize examples of each. A) Polyploidy B) Aneuploidy

Polyploidy: error resulting in NO separation of chromosomes, creating too many sets ex: Tetraploids (32 chromosomes) Aneuploidy: failure of 1 chromosome to separate ex: Down, Jacobs, Triplo-X, and Klinefelter Syndrome

During which phase of meiosis does synapsis and crossing over occur? Define each.

Prophase 1

How can asexual species accumulate variations in the population rapidly enough to adapt and survive a changing environment?

When asexual organisms evolve, they typically do so very quickly after a sudden mutation and do not require multiple generations to accumulate adaptations

The diploid cells of your body are ___________ (somatic cells or gametes) and are formed by mitosis.

somatic cells

Describe each phase of Meiosis 1 and 2. If something separates or divides, be specific as to what divides (cells, nuclei, sister chromatids, homologs, etc.) Notice that "prometaphase" is not listed.) A) Prophase 1: B) Metaphase 1: C) Anaphase 1: D) Telophase 1: E) Cytokinesis: F) Prophase 2: G) Metaphase 2: H) Anaphase 2: I) Telophase 2: J) Cytokinesis:

Prophase I: - Nucleus breaks down - Chromosomes condense & become visible - Homologous chromosomes pair & form bivalents/synapses Metaphase I: - Paired homologs line up randomly along equator - Independent Assortment Anaphase I: - homologs separate to opposite poles Telophase I: - the 2n cell divides into 2 1n cells - spindle fibers break down - new nuclei form Cytokinesis I: - cell splits in 2, each cell now has 2 chromosomes

What are somatic cells and what are germ cells?

Somatic Cells:- Body cells/Building blocks of the body- Diploid cells (2n)- Can only undergo Mitosis Germs Cells:- Produce gametes- Only cells that can undergo Mitosis & Meiosis

How many functional gametes are produced from one parent cell by Spermatogenesis and Oogenesis?

Spermatogenesis: 4 sperm cells for each germ cell Oogenesis: 1 egg cell for each germ cell

1 Nondisjunction A) Definition: B) How does it occur? C) When does it occur? Possible outcomes

The failure of chromatids to separate during (any) Anaphase - occurs when spindle fibers don't attach or break - occurs during Anaphase - can result in Polyploidy or Aneuploidy, causing miscarriage or genetic disorders, such as Down Syndrome