Biology 1.4

Question 1

G1 Phase

Answer 1

Increase cytoplasm, protein synthesis, duplication of organelles

Question 2

S Phase

Answer 2

Synthesis, DNA and centrosomes duplicated and cell continues to grow

Question 3

G2 Phase

Answer 3

Cell continues to grow and prepares for division

Question 4

Mitosis

Answer 4

Division of nuclear DNA, PMAT

Question 5

Cytokinesis

Answer 5

Division of cytoplasm into 2 cells

Question 6

SA to volume ratio

Answer 6

As cell grows, volume increases faster than SA. Membrane cannot support cell which causes cell division, shape change or apoptosis

Question 7

Genome to volume ratio

Answer 7

Volume increases as cell grows but genome size remains the same. Genome cannot make enough material to regulate cell activities for the larger cell volume

Question 8

G1 cell checkpoint

Answer 8

Check cell to see if it is in proper conditions for division such as environment and healthiness of DNA.

Question 9

G0

Answer 9

Cell enters this phase if it does not pass the G1 cell checkpoint. It stays here until the cell is ready for division

Question 10

G2 cell checkpoint

Answer 10

Checks if DNA is undamaged and properly replicated

Question 11

M cell checkpoint

Answer 11

Checks if chromosomes are properly attached to microtubules for proper division of genome

Question 12

CDK’s (Cyclin-dependent kinases)

Answer 12

When bound by cyclin, CDK’s phosphorylate other enzymes to switch them to their active configuration. These enzymes regulate the cell and can act as checkpoint markers.

Question 13

Growth Factors

Answer 13

A signalling molecule released by damaged cells that can bind to a membrane receptor of another cell, causing it to undergo division

Question 14

Density-dependent inhibition

Answer 14

If cells in an area are too dense, they will stop dividing

Question 15

Anchorage dependence

Answer 15

Cells need to be anchored to a surface to undergo division.

Question 16

Cytokinesis in plants

Answer 16

Vesicles from Golgi apparatus align at plane of division and fuse to form a cell plate. Cell plate becomes plasma-membrane of daughters. Next, cell wall forms around the 2 cells

Question 17

Cytokinesis in animals

Answer 17

Microfilaments form a ring along division plate and shorten/tighten which causes the cell to pinch into a cleavage furrow

Question 18

Prophase

Answer 18

Duplicated chromatin condenses to sister chromatids. Nucleoli disappears and nuclear envelope breaks down. Mitotic spindle forms, centrosomes move to opposite poles and microtubules develop.

Question 19

Metaphase

Answer 19

Sister chromatids align at metaphase plate and each one is attached to microtubule from opposite poles at their kinetochore.

Question 20

Anaphase

Answer 20

Microtubules pull each chromosome to opposite poles. Each pole has complete set of chromosomes with same genetic content as original cell

Question 21

Telophase

Answer 21

Nuclear envelope reappears around each pole, forming 2 separate nuclei. Chromosomes decondense to chromatin and nucleoli appears

Question 22

Meiosis

Answer 22

In males and females, produces haploid germ cells called sperm and oocytes. Produces genetically distinct germ cells. Starts with interphase followed by meiosis I and meiosis II

Question 23

Prophase I

Answer 23

Chromatin condenses to chromosomes, nucleolus disappears and spindle apparatus develops. Synapsis, the physical pairing of maternal and paternal homologous chromosomes, occur to form a tetrad/bivalent. Afterwards, synaptonemal complex forms between the homologous chromosomes and crossing over occurs between non-sister chromatids at the crossed chiasmata point

Question 24

Metaphase I

Answer 24

Tetrads align randomly, called independent assortment at metaphase plate. Microtubules from opposite poles connect at kinetochore of each pair of sister chromatids

Question 25

Anaphase I

Answer 25

Tetrads uncouple as each pair of sister chromatids are pulled to opposite poles

Question 26

Telophase I

Answer 26

Nuclear envelope reforms. New nuclei has half the original amount of chromosomes but each chromosome is present as a duplicate. Depending on species, the cell may or may not undergo cytokinesis.

Question 27

Meiosis II

Answer 27

No DNA replication, same as meiosis I but no chiasmata or crossing over

Question 28

Cytokinesis in meiosis

Answer 28

Occurs after telophase II, results in 4 haploid cells. Each cell has half the original number of chromosomes and only one sister chromatid.

Question 29

Random fertilization

Answer 29

Fertilization of oocyte occurs at random by sperm cell to produce diploid zygote.

Question 30

Induction

Answer 30

The process of a cell influencing the development of another cell

Question 31

Crossing over

Answer 31

Prophase I, exchange of genetic info between maternal and paternal homologous chromosomes

Question 32

Independent assortment

Answer 32

Metaphase I, tetrads line up randomly at metaphase plate

Question 33

Random fertilization

Answer 33

Any sperm fertilizes the egg randomly

Question 34

Asexual reproduction in eukaryotes

Answer 34

Only in certain organisms (ex. ferns). Undergo meiotic division to make haploid spores. Spores undergo mitosis to make multicellular haploid gametophyte which produces gametes (germ cells). 2 gametes fuse to make diploid sporophyte that can undergo meiosis to make haploid spores

Question 35

Binary fission in prokaryotes

Answer 35

Occur in certain organelles (mitochondria and chloroplasts) and some single-celled eukaryotes. Circular DNA in nucleoid region of bacteria are replicated from the origin of replication. 2 plasmids move to opposite ends of the cell and then divide by cytokinesis. Makes 2 genetically identical bacterial daughter cells.