Biology - Unit 4, Cell Cycle & Reproduction

Chromatin

Chromatin

a form of DNA is “unwound” in the nucleus of a cell

• chromatin is formed during cell division

Chromosomes

a form of DNA that is “wound” into a structure

Autosomes

any chromosome that is not a sex chromosome

Karyotypes

• images of a persons chromosomes that shows the biological sex & possible chromosomal abnormalities

Monosomy

a chromosomal abnormality that causes a cell to have a chromosome pair that is missing one chromosome

Trisomy

a chromosomal abnormality that causes a cell to have a chromosome pair that contains an extra chromosome.

Interphase

part of the cell life cycle that is not involved in cell division.

• includes G1, S, & G2

G1

cells grow & perform normal functions like cellular respiration, photosynthesis, and protein synthesis.

G2

cells prepare for division / mitosis by growing more in size and replicating organelles.

Synthesis (S)

cells replicate their DNA in order to give the newly divided cells a copy.

Cytokinesis

the division of the cytoplasm

Somatic Cells

body cells (diploid)

Ploidy

the number of each type of chromosome in a cell

• the ploidy of cells differs based on the type of cell

Haploid

a cell that has 1 complete set of chromosomes

Diploid

a cell that has 2 sets of chromosomes from both parents

Prophase

the nuclear membrane dissolves and DNA condenses into chromosome form.

• crossing over occurs in Prophase 1 (the first phase in the process)

Metaphase

chromosomes line up in the middle of the cell.

• independent assortment occurs in metaphase I.

Anaphase

chromosomes are pulled apart and move to either end of the cell.

• chromosomal abnormalities / nondisjunction can occur during anaphase

Telophase

a nuclear membrane begins to form around each set of chromosomes & the cell membrane grows inward (beginning to pinch the cell into two.)

Gametes

sex cells (egg & sperm)

Homologous Pairs

they are chromosomes that are inherited from both parents.

• they have the same genes in the same places and are the same size and shape, but have different genetic information in them.

Meiosis I

the separation of homologous pairs (produces 2 cells)

Meiosis II

separation of sister chromatids (produces 4 cells)

Crossing over

Crossing over occurs in prophase 1 (the first phase in the process).

• it can be described as homologous chromosomes exchanging genetic information by literally crossing over parts of the chromosome.

Independent assortment

independent separation of genes (during the formation of gametes)

Nondisjunction

an error in meiosis where homologous chromosomes fail to separate (occurs during anaphase 1)

Sister chromatids

replicated (identical) chromosomes

• that are connected by a centromere

Mitosis

 a form of cell division that is asexual, and produces genetically identical cells.

• division of the nucleus (chromosomes and DNA)

• P.M.A.T

Sexual reproduction

two parents that create genetically different offspring

Asexual reproduction

only 1 parent that creates genetically identical offspring

Fertilization

the fusion of an egg & sperm cell

What happens in the S phase?

cells replicate their DNA

Why is the S phase so important to cell division?

• DNA must be replicated in order for both of the daughter cells to have the correct # of genetic information / chromosomes

In what phase should healthy cells spend most of their time?

interphase

What factors help ensure that cell division in under control?

cell checkpoints

How do cancer cells behave differently than healthy cells?

cancer cells uncontrollably divide (cell division)

What factors can lead to cancer cells?

UV radiation, chemical exposure, carcinogens

How do cancer treatments work to target cancer cells?

they target quickly spreading cells, and kill the cells

Why do cancer treatments cause side effects such as hair loss, fatigue, or nausea?

As cancer treatments target all fast replicating cells, it affects a persons digestive system, hair follicles, and skin

Advantage of sexual reproduction

• genetic diversity

Disadvantages of sexual reproduction

• greater chance of mutation

• requires a lot of energy / time

Advantages of asexual reproduction

• rapid population growth

• requires less energy

• all organisms are capable of reproduction (regardless of gender)

Disadvantages of asexual reproduction

• non genetic diversity

• more susceptible to diseases

What is the basic process of meiosis?

• there are 2 round of P.M.A.T

• metaphase 1 = separates homologous chromosomes

• metaphase 2 = separates sister chromatids

What is the purpose of meiosis?

to create haploid gametes

What is produced in meiosis?

sex cells

How does meiosis relate to sexual reproduction?

in fertilization opposing gametes fuse together and create a diploid zygote

What are similarities between mitosis & meiosis?

cell division that takes place in 2 types of cells in the body

What are similarities between somatic & gamete cells?

they are both types of cells

What are similarities between haploids & diploids?

the amount of chromatids in each set of chromosomes

• haploid = 1 in each set

• diploid = 2 in each set

What are similarities between sexual & asexual reproduction?

both are types of reproduction

What are similarities between crossing-over & independent assortment?

both are ways that offspring gain genetic variability in meiosis?

What are similarities between a trisomy & a monosomy?

both are types of chromosomal abnormalities

• caused by nondisjunction