Chapter 9 & 10 ~ The Cell Cyle & Meiosis And Sexual Life Cycles

Question 1

Cell division

Answer 1

The continuity of life is based on the reproduction of cells

Roles:
- division of one prokaryo cell reproduces an entire organism
- enables multicellular eukaryos to develop from a 1 cell
- cell division continues after growth (renewal and repair, replacing dead cells from tears)

Question 2

Asexual reproduction

Answer 2

Process:
- single parent organism
- parent cell undergoes mitosis to produce genetically identical offspring
- no exchange of genetic material btwn different individuals

Products:
- genetically identical individual
- clones of the parent
- genetic diversity is limited

Question 3

Sexual reproduction

Answer 3

Process:
- two parent organisms contributing genetic material
- specialized cells are produced (chromosome number is 1/2)
- fertilization occurs and combines genetic material

Products:
- genetically unique individuals
- inherit a combination of genetic material (genetic diversity)
- recombination

Question 4

Chromosomes

Answer 4

Long, thread like structure found in the nucleus and are composed of DNA and associated proteins.

Question 5

Chromatin

Answer 5

The entire complex of DNA and proteins that is the building material of chromosomes

Question 6

Chromosome Duplication

Answer 6

Interphase (chromosome duplication in S phase)
- after duplication, there are 2 sister chromatids connected along their lengths by sister chromatid cohesion

Mitotic phase (duplicated chromosomes are separated into daughter cells)

Cell division (chromatids are pulled to opposing ends)

Question 7

Interphase

Answer 7

G1 phase: cell growth, function, checking for DNA damage, decision for cell division

S phase: DNA replication, formation of sister chromatids, accuracy and fidelity, protein synthesis, completion of DNA replication

G2 phase: nuclear envelop encloses nucleus, two centrosomes are formed, chromosomes are not seen separated yet

Question 8

Prophase

Answer 8

Chromatin becomes more tightly coiled
Nucleoli disappears
Duplicated chromosomes appear as two sister chromatids
Mitotic spindle begins to form
Centrosomes move away from each other

Question 9

Prometaphase

Answer 9

Nuclear envelope breaks
Microtubules invade nuclear area
Chromosomes become more condensed

Question 10

Metaphase

Answer 10

Centrosomes are not at opposite poles of the cell
Chromosomes have arrived at the metaphase plate

Question 11

Anaphase

Answer 11

Shortest stage of mitosis
Two sister chromatids suddenly part becoming chromosomes
Chromosomes move toward opposite ends of the cell
The cell elongates
Two ends of the cells have a complete collection of chromosomes

Question 12

Telophase

Answer 12

2 daughter nuclei form in the cell
Nucleoli reappear
Chromosomes become less condensed
Spindle microtubules are depolymerized
Mitosis is complete

Question 13

Cytokinesis (animal cell)

Answer 13

Division of the cytoplasm
For action of cleavage furrows
Cell membrane pinching
Formation of 2 daughter cells

Question 14

Cytokinesis (plant cells)

Answer 14

Vesicle formation
Cell plate formation
Cell wall deposition
Formation of 2 daughter cells

Question 15

Cell cycle control system

Answer 15

Checkpoints
Cell Cycle phases
Cell signaling

Question 16

Cell cycle control system (consequences of errors)

Answer 16

Cancer
Genetic mutation
Cell death
Cellular dysfunction
Aging
Developmental abnormalities

Question 17

How are cancer cells different from healthy cells?

Answer 17

uncontrolled growth
Loss of contact inhibition
Genetic mutations
Autonomy (evade signals from other cells)
Immortality
Invasion and metastasis
Resistance to apoptosis
Angiogenesis (induce formation of new blood vessels)
Heterogeneity

Question 18

Benign tumors

Answer 18

non cancerous that do not invade nearby tissues and organs
Resemble normal cells
Do not metastasize
Not life threatening and can be surgically removed

Question 19

Malignant tumors

Answer 19

Cancerous growths characterized by uncontrolled growth
Abnormal behavior (uncontrolled division, evade programmed death)
Ability to metastasize
Can be life threatening

Question 20

“Slash, Burn, Poison”

Answer 20

Surgery (slash)
Radiation therapy (burn)
Chemotherapy (poison)

Question 21

How to reduce the risks of developing cancer

Answer 21

Healthy diet
Regular physical activity
Tobacco avoidance
Sun protection
Limit alcohol consumption
Cancer screenings
Vaccinations
Healthy weight
Limit exposure to radiation
Breastfeeding

Question 22

Sex chromosomes

Answer 22

Pair of chromosomes that determine an individual’s sex

2 sets in humans: X and Y (males: XY , females: XX)

Question 23

Autosomes

Answer 23

All the chromosomes in an organism’s genome except for the sex chromosome

Question 24

Somatic Cells

Answer 24

Non-reproductive cells that make up the tissues of the organs in the organism

Are diploid (2 sets of chromosomes, one from each parent)

Question 25

Gametes

Answer 25

Reproductive cells involved in sexual reproduction

Sperm and Egg

Are haploid (1 set of chromosomes)

Question 26

Diploid

Answer 26

2 sets of chromosomes, one from each parent

Humans have a total of 46 chromosomes (23 pairs)

Found in somatic cells

Question 27

Haploid

Answer 27

One set of chromosomes

23 chromosomes (1/2 the ones in diploid)

Sperm & Egg

Question 28

Why the production of haploid gametes in sexually reproducing organisms is necessary

Answer 28

Combination of genetic material
Genetic variation
Recombination
Purging harmful mutations
Dilution of recessive traits
Evolutionary advantage
Species survival

Question 29

Meiosis I (process)

Answer 29

Prophase I: chromosomes condense, homologous pair up, genetic recombination occurs through crossing over

Metaphase I: homologous chromosomes line at the equator (1 chromosome from each parent)

Anaphase I: homologous chromosomes are separated and pulled to opposite poles (ec gets 1 set of chromosomes)

Telophase I: 2 haploid daughter cells are formed with a unique combination of chromosomes

Question 30

Meiosis I (products)

Answer 30

2 genetically distinct (from crossing over) haploid daughter cells, each with 1/2 the number of chromosomes as original diploid

Question 31

Meiosis II (process)

Answer 31

Prophase II: chromosomes condense again in the two haploid daughter cells from meiosis I

Metaphase II: chromosomes align at the equator

Anaphase II: sister chromatids are separated and pulled to opposite poles of the cell

Telophase II: 4 genetically unique haploid daughter cells are produced

Question 32

Meiosis II (product)

Answer 32

4 haploid daughter cells with 1/2 the number of chromosomes as original diploid cell. They are the final gametes in sexual reproduction

Question 33

Genetic diversity in Meiosis

Answer 33

Maternal and paternal chromosomes can be distributed randomly into different gametes

The number of possible combinations of chromosomes that can result from assortment is 2^n (n= haploid chromosomes)

Offspring can inherit a wide variety of genetic combinations from their parents leading to genetic diversity

Question 34

Genetic diversity in fertilization

Answer 34

In sexually reproducing organisms, there are many combinations of super and egg gametes due to meiosis

The sperm when fertilizing the egg is by chance. Random fertilization combines genetic material from two parents in a unique way for each offspring, adding to genetic diversity

Question 35

Genetic diversity in crossing over

Answer 35

Occurs during meiosis I and is the recombination of genes on the chromosomes

the exchange of genetic material between chromatids of homologous chromosomes creates new combinations which contribute to genetic diversity

Question 36

Nondisjunction

Answer 36

A chromosomal abnormality that occurs during meiosis when chromosomes fail to separate properly; can lead to incorrect number of chromosomes in gametes

Question 37

Nondisjunction in autosomes

Answer 37

Trisomy: nondisjunction that results in the presence of an extra autosome in the zygote leads to trisomy (Down syndrome) which results from an extra copy of chromosome 21

Monosomy: loss of one autosome, leading to monosomy. Common example is Turner syndrome, caused from the loss of one X chromosome in females

Question 38

Nondisjunction in sex chromosomes

Answer 38

Sex chromosome trisomy: can lead to conditions where there is an extra X and Y chromosome; Klinefelter syndrome occurs in males who have an extra X chromosome

Sex chromosome monosomy: loss of a sex chromosome; can lead to turner syndrome