BIO 110 Exam 2 - Cell Cycle, Mitosis and Meiosis

cell division

Process by which a parent cell divides into two new daughter cells making genetic clones

cell cycle

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

DNA

deoxyribonucleic acid, a self-replicating material present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

Chromosomes

threadlike structures made of DNA molecules that contain the genes

How many chromosomes do humans have?

46 (23 pairs)

somatic cells

Any cells in the body other than reproductive cells

Gametes

reproductive cells, have only half the number of chromosomes as body cells (23)

Genome

All the genetic information in an organism; all of an organism's chromosomes.

Gene

sequence of DNA that codes for a protein and thus determines a trait

What are the phases of the cell cycle?

interphase, prophase, metaphase, anaphase, telophase, cytokinesis

chomatin

stringy uncoiled DNA and its associated proteins found in chromosomes.

centrosomes

an organelle near the nucleus of a cell that contains the centrioles

Centrioles

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

spindle fibers

help pull apart the cell during replication and are made up of micrtubules

microtubes

Spiral strands of protein molecules that form a tubelike structure

kinetochore

A specialized region on the centromere that links each sister chromatid to the mitotic spindle.

Centromere

Area where the chromatids of a chromosome are attached

Chromatid

one half of a duplicated chromosome

metaphase plate

Plane midway between the two poles of the cell where chromosomes line up during metaphase.

What happens Interphase? (Mitosis and Meiosis)

Cell prepares to divide

-Chromosomes are replicated (Still in loose chromatin form)

-Centrosomes replicated

What happens during prophase?

First stage of cell division

-Chromosomes condense

-Spindle and aster microtubules form

-Centrosomes migrate towards poles

What happens during prometaphase?

-Nuclear envelope breaks down

-Chromosomes fully condensed

-Centrosomes migrate toward poles

-Spindle attaches to kinetochore on centromere

What happens during metaphase?

-Centrosomes reach poles

-Chromosomes aligned on the metaphase plate

What happens during anaphase?

Sister chromatids separate and move to opposite towards opposite poles

(Called daughter chromosomes)

What happens during telophase?

-Nuclear envelopes form around the identical sets of chromosomes at the two poles of the cell.

-The chromosomes uncoil and return to chromatin

-Spindle and asters broken down

What happens during cytokinesis?

division of the cytoplasm to form two separate daughter cells (pinching of cell)

Mitosis

a process where a single cell divides into two identical daughter cells

clevage furrow

Forms in animals to separate the 2 cells in cytokinesis. Formed by a contractile ring of actin filaments

cell plate

In a plant cell, midline of dividing cells. Becomes the cell wall eventually. (This is how cytokinesis happens in plants)

binary fission

A form of asexual reproduction in prokaryotes by which one cell divides into two identical cells

origin of replication

where DNA replication begins for circular chromosomes

circular chromosome

Only found in Bacteria and Archaea

What are the 3 phases of interphase?

G1 phase (1st gap phase), S phase (synthesis), G2 phase (2nd gap phase)

What happens during G1 of interphase?

Cells grow

What happens during S of Interphase?

DNA Replication

What happens during G2 of interphase?

Prepares for cell division

asexual reproduction

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

What is the G0 of interphase?

Where cells stop dividing.

When is DNA replicated?

S phase of interphase

How are chromosomes arranged differently in prokaryotes and eukaryotes?

Eukaryotes have tightly packed linear chromosomes that are found in the nucleus.

Prokaryotes have circular chromosomes located in the cytoplasm.

How does cytokinesis differ in plant and animal cells?

In animal cells, a cleavage furrow forms and the contractile ring pinches the cell into two.

In plant cells, a cell plate forms in the middle of a cell which eventually splits and creates two new cell walls. There are NO contractile rings in plant cells

Meiosis

a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells

Genetics

the study of heredity of traits and their variation

Genes

DNA segments that serve as the key functional units in hereditary transmission. Passed from parent to offspring.

Locus

Location of a gene on a chromosome

Meiosis I

Homologous chromosomes separate into two sister chromatids

Meiosis II

the second phase of meiosis consists of two sister chromatids separating into 4 haploid cells (Very similar to mitosis)

Budding

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism

parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs. (offspring develop from SINGLE cell)

What produces gametes?

Germ cells

germ cells (gametes)

sex cells (sperm and egg)

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Are gametes haploid or diploid?

haploid (1n)

n

haploid (23 chromosomes)

2n

diploid (46 chromosomes)

homologous pairs (homologs)

A pair of chromosomes of the same type, one from each parent.

X and Y chromosomes

sex chromosomes; XX female; XY male

Diploid

an organism or cell having two sets of homologous chromosomes

sporophyte

Diploid, or spore-producing, phase of an organism. Makes haploid spores by meiosis.

gametophyte

Haploid, or gamete-producing, phase of an organism

How does meiosis occur in fungi?

Without multicellular offspring developing.

What are the steps of meiosis?

Interphase, Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Anaphase 2, Telophase 2

What does meiosis 1 start with?

1 - 2n Parent cell (diploid)

What does meiosis 1 end with?

2 - n daughter cells (haploid)

What does meiosis 2 start with?

2 - n daughter cells (haploid)

What does meiosis 2 end with?

4 - n daughter cells (haploid)

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis. (One chromosome becomes a mix of both parental non-sister chromatids. (red and blue))

When does crossing over occur?

Prophase I of meiosis

What are the steps of crossing over?

1. Non-sister chromatids (homologs) align based on gene location.

2. A protein makes identical breaks in the DNA.

3. Synapsis forms and holds the homologs tightly together.

4. DNA breaks are repaired but now connected across the non-sister chromatids.

5. Synapsis proteins are removed but the crossed over structure remains.

End result is Recombinant chromosomes

recombinant chromosomes

Chromosomes that carry genes from each parent.

genetic variation

The variety of different types of genes in a species or population.

What are the 3 things that contribute to genetic variation?

1. Independent assortment of chromosomes

2. Random fertilization

3. Crossing over

law of independent assortment

Mendel's second law, stating that allele pairs separate from one another during gamete formation

Fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell

Autosomes

Any chromosome that is not a sex chromosome

Chaismata

Regions where the homologous chromosomes are held together during prophase I (Center of the X shape)

life cycle

The generation-to-generation sequence of stages in the reproductive history of an organism.

What is the difference between diploid and haploid cells?

diploid cells contain two complete sets of chromosomes. Haploid cells only contain one complete chromosome set.

What is segregated during Meiosis 1?

homologous chromosomes

What is the major difference between Meiosis and Mitosis?

Mitosis involves the division of body cells, while meiosis involves the division of sex cells. The division of a cell occurs once in mitosis but twice in meiosis. Two daughter cells are produced after mitosis and cytoplasmic division, while four daughter cells are produced after meiosis

What is similar about Meiosis and Mitosis?

They are both preceded by interphase (which includes DNA replication) They both divide according to a common pathway (prophase → metaphase → anaphase → telophase) They both split their cells via cytokinesis.

What is the difference between sexual and asexual reproduction?

Asexual reproduction generates offspring that are genetically identical to a single parent. In sexual reproduction, two parents contribute genetic information to produce unique offspring.

What is the order of phases in both Mitosis and Meiosis?

IPMAT (I Pee Mat)

Interphase, Prophase, Metaphase, Anaphase, Telophase

During which phase do chromatids condense?

Prophase

During which phase does a nuclear envelop FORM?

Telophase

During which phase does a nuclear envelop fragment?

(Pro)metaphase

During which phase do sister chromatids split and move to opposite poles.

Anaphase

During which phase do cells split into two new cells?

Telophase (Cytokinesis)

During which phase do the spindles attach to the kinetochore?

(Pro)metaphase

During which phase are chromosomes replicated?

Interphase

What phase will you find chromatin in?

Interphase (Begining) and Telophase (End)

During which phase do centrosomes reach the poles?

Metaphase

During which phase do chromosomes align on the metaphase plate?

Metaphase

What phase takes the longest in the cell cycle?

Interphase