General Biology I (BIO 101) Lecture Chapter 8 Objectives:

What are two similarities and two differences between mitosis and meiosis? (NOTE: students should be able to illustrate the parent cell and resulting daughter cells for mitosis and meiosis I and II and label which cells are diploid and haploid.)

-both occur in diploid cells -DNA replication occurs during interphase for both -mitosis produces two daughter cells while meiosis produces four. -division occurs once during mitosis, and twice during meiosis

What are the three stages of binary fission of prokaryotes? (HINT: students should understand duplication, elongation, and division.)

-duplication -division -elongation.

How many sex chromosomes are found in human somatic cells?

1

binary fission steps

1. Cell elongates and DNA is replicated 2. Cell wall and plasma membrane begin to constrict 3. Cross-wall forms, completely separating the two DNA copies 4. Cells separate

How many autosomes are found in human somatic cells?

22

How is 2N used to determine genetic recombination through meiosis?

2n is the formula for the number of combinations of genetic variation a parent can produce

Deletion

A change to a chromosome in which a fragment of the chromosome is removed.

cell plate

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

binary fission

A form of asexual reproduction in which one cell divides to form two identical cells.

asexual reproduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.

telophase

After the chromosome seperates, the cell seals off, Final Phase of Mitosis.

Haploid

An organism or cell having only one complete set of chromosomes.

autosomes

Any chromosome that is not a sex chromosome

centromeres

Area where the chromatids of a chromosome are attached

Interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

genes

Chemical factors that determine traits

prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

metaphase II

Chromosomes line up at the equator.

homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure

Telophase I (Meiosis)

Cytokinesis occurs, the result are two haploid daughter cells

S phase

DNA is replicated

Elongation in binary fission

Elongation of the cell and movement of DNA copies

Nondisjunction

Error in meiosis in which homologous chromosomes fail to separate.

chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

Metaphase I (Meiosis)

Tetrads are lined up at the metaphase plate; Spindle fibers attach

Anaphase I (Meiosis)

Tetrads split up and head to opposite poles

cleavage furrow

The area of the cell membrane that pinches in and eventually separates the dividing cell

prophase II

The duplicated chromosomes and spindle fibers reappear in each new cell.

mitotic phase

The phase of the cell cycle that includes mitosis and cytokinesis.

how does independent orientation contribute to genetic recombination?

The physical basis of recombination between unlinked genes is the random orientation of homologous chromosomes at metaphase I of meiosis, which leads to the independent assortment of the two unlinked genes

genetic recombination

The regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents.

G2 phase

The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.

prometaphase

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

Inversion (chromosomal)

a segment of the chromosome order is switched

G1 phase of interphase

cell grows: increase in size and synthesize new proteins and organelles

How do plant cells undergo cytokinesis?

cell plate

What are three factors that control cell division?

checkpoints, growth factor, density dependent inhibition

How do animal cells undergo cytokinesis?

cleavage furrow

Diploid

containing two complete sets of chromosomes, one from each parent.

Division in binary fission

division into two daughter cells

Cytokinesis

division of the cytoplasm

Mitosis

division of the nucleus

Duplication in binary fission

duplication of chromosomes and separation of copies

Zygote

fertilized egg

One advantage of sexual reproduction

genetic diversity

Prophase I (Meiosis)

homologous chromosomes pair up and form tetrads, crossing over occurs

how does crossing over contribute to genetic recombination?

if crossing over occurs between the different parental genes, there will be genetic recombination

When does independent orientation occur during the cell cycle?

metaphase I

Translocation

moves a segment from one chromosome to another

one disadvantage of asexual reproduction

no genetic variation

one advantage of asexual reproduction

only one parent is needed

metaphase

phase of mitosis in which the chromosomes line up across the center of the cell

Meiosis purpose

produce gametes

Duplication

repeats a segment

What are three uses for cell division?

reproduction of single cells, cell repair, and growth and development.

cell cycle

series of events that cells go through as they grow and divide

Gametes

sex cells

anaphase II

sister chromatids separate

One disadvantage of sexual reproduction

takes more time, and requires a mate

crossing over

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

chromosomes

threadlike structures made of DNA molecules that contain the genes

sexual reproduction

type of reproduction in which cells from two parents unite to form the first cell of a new organism

cell cycle checkpoints

Points of transition between different phases of the cell cycle, which are regulated by cyclins and cyclin-dependent kinases (Cdk's).

telophase II

Nuclear membrane reforms, cytoplasm divides, 4 daughter cells formed

sex chromosomes

One of the 23 pairs of chromosomes in the human, contains genes that will determine the sex of the individual.

anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

independent orientation

Random arrangement of homologous chromosomes during metaphase I, leading to genetic variation

Fertilization

Fusion of an egg and sperm cell

sister chromatids

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.

Loci

Location of a gene on a chromosome

somatic cells

any cell of a living organism other than the reproductive cells.