Chapter 8 final study

Describe the stages of the cell cycle

(1) Interphase: when mitosis is going to happen, but not yet (2) Prophase: when mitosos really starts, chromasomes begins to wrap around histones, nuclear envelope breaks down (3) Metaphase: sister chromatids line up (4) Anaphase: chromatids pull apart, each cell is getting sister chromatids as they move twowad the poles that are on opposite sides of the cell (5) Telaphase: see clevage furrow, pinching together in the middle (6) Cytokinesis: division into two daughter cells is completed

Explain how anchorage, cell density, and chemical growth factors control cell division.

A growth factor is a protein made by certain body cells that stimulates cell division. Cells are dependent on anchorage (contact with a solid surface) to divide. Density plays an important factor for once the cell has formed a complete layer, it stops dividing. Cells are unable to divide without if an essential nutrient is left out of the culture.

Compare the parent-offspring relationship in asexual and sexual reproduction

Asexual reproduction produces offspring identical to original cell, and only uses the genes of one parent; Sexual reproduction produces offspring similar to the parents but have variation in traits.

Explain how cancerous cells are different from healthy cells.

Cancerous cells divide uncontrollably, often with the absence of growth factors. They spread to other tissues, through the circulatory system. Growth without being inhibited by other cells.

Explain why cell division is essential for prokaryotic and eukaryotic life.

Cell division enables single cells to reproduce. Cell division also repairs and replaces cells that die.

Explain how daughter prokaryotic chromosomes are separated from each other during binary fission.

First, duplication of the chromosomes and separation of the copies. Second. continued elongation of the cell and movement of copies. Third, division into two daughter cells.

Explain how genetic variation is produced in sexually reproducing organisms.

Genetic variation in gametes results from independent orientation at metaphase I and random fertilization.

Compare cytokinesis in animal and plant cells.

In plants, the division of the cytoplasm into two cells, a cell plate forms in the meddles, results in two daughter cells with their own cell wall. In animal cells, cytokinesis occurs by a process known as cleavage (the first sign is the cleavege furrow).

Explain how and why karyotyping is performed.

Karyotyping is a test to examine chromosomes in a sample of cells. This test can help identify genetic problems as the cause of a disorder or disease. The test can be performed on almost any tissue.

Explain why sexual reproduction requires meiosis.

Meiosis reduces the chromosome number in half, so the chromosome number wouldn't double every generation.

Compare mitosis and meiosis, noting similarities and differences.

Mitosis and meiosis both begin with diploid parent cells that have chromosomes duplicated during the previous interphase. However, the end products differ. Mitosis produces two genetically identical diploid somatic daughter cells. Meiosis produces four genetically unique haploid gametes.

Describe the consequences of abnormal numbers of sex chromosomes.

Most Common Human Sex Chromosome Abnormalities XXY Klinefelter Syndrome (male) XYY None (normal male) XXX None (normal female) XO Turner's Syndrome (female)

Define nondisjunction, explain how it can occur, and describe what can result.

Nondisjunction is the failure of chromosomes or chromatids to separate normally during meiosis. This can happen during meiosis I, if both members of a homologous pair go to one pole, or meiosis II, if both sister chromatids go to one pole. Fertilization after nondisjunction yields zygotes with altered numbers of chromosomes.

Explain how new species form from errors in cell division.

Occurs when an organism has more than two sets of homologous chromosomes in its body cells. This happens when a meiosis fails to occur in the reproductive organs and gametes are instead produced by mitosis, the gametes will be diploid.

Describe the functions of mitosis.

Provides for growth, cell replacement, and asexual reproduction. Mitosis produces two genetically identical diploid somatic daughter cells.

Compare the structure of prokaryotic and eukaryotic chromosomes.

The chromosome of a prokaryote is typically a single circular DNA molecule associated with proteins and much smaller than those of eukaryotes. Eukaryotic cells are more complex and larger than prokaryotic cells, have more genes, and store most of their genes on multiple chromosomes within the nucleus.

Describe the causes and symptoms of Down syndrome.

The most common form of Down syndrome is known as Trisomy 21, a condition where individuals have 47 chromosomes in each cell instead of 46. This is caused by an error in cell division called nondisjunction, which leaves a sperm or egg cell with an extra copy of chromosome 21 before or at conception

Describe the main types of chromosomal changes. Explain why cancer is not usually inherited.

deletion- a segment of chromosome is removed inversion- a segment of chromosome is removed then reinserted "backwards" to its original orientation duplication- a segment of chromosome is copied and inserted into the homologous chromosome translocation - segments of two nonhomologous chromosomes swap locations with one another (how some forms of cancer are started) These "changes" can only be passed on to offspring if they occur in a gonad cell (testes in males and ovaries in females). In any somatic cell, the changes will not affect future generations.

Explain how chromosomes are paired.

identical genes, length, and position

List the phases of meiosis I and meiosis II and describe the events characteristic of each phase.

meiosis 1= prophase 1-chromosomes split and coil and cross over spindle is formed metaphase 1-lined up at central plate anaphase 1-split apart telophase 1 and cytokinesis- cleavage furrow formed and cells split apart

List the phases of mitosis and describe the events characteristic of each phase.

prophase-In the nucleus, chromosomes become more tightly coiled and folded. prometaphase- The nuclear envelope breaks into fragments and disappears. metaphase-sister chromatids line up to divide anaphase- chromatids devide and move toward poles telophase-cell begins to pinch in two

Distinguish between somatic cells and gametes and between diploid cells and haploid cells.

somatic cell is a cell in the human body/has 46 chromosomes gametes are sex cells haploid single chromosome set, one member of each homologous pair (n) (n=23) diploid cells are cells with two homologous sets of chromosomes (2n) (2n=46)