Unit 4 cellular structure and fuction- Cell size and cell cycle

Question 1

What are the phases of interphase?

Answer 1

G1( gap phase/ growth phase 1), S/synthesis phase, and G2/ growth phase 2

Question 2

what occurs during the G1 phase of interphase?

Answer 2

cell growth and protein synthesis

Question 3

What occurs during the S/synthesis phase of interphase

Answer 3

DNA is synthesized and replicated

Question 4

What occurs during the second gap phase of interphase?

Answer 4

Growth, protein synthesis, and organelle development
- All chromosomes are fully replicated after the S-phase, so the cell continues to grow and prepare for division.

Question 5

What is interphase?

Answer 5

period of the cell cycle between cell divisions in which the cell grows and prepares for cell division. also called the somatic (non-productive) phase of the cell cycle
- the cell spends over 90 percent of the cell cycle in interphase preparing for division.

Question 6

What are chromosomes?

Answer 6

threadlike structures within the nucleus that contain genetic information that is passed on in cell division.

Question 7

Why do multicellular organisms engage in cell division?

Answer 7

cell division allows the cell to grow develop and it is necessary for repair and renewal

Question 8

why do unicellular organisms engage in cell division?

Answer 8

it is how they reproduce, lliterally cloning themselves through citosis (asexual reproduction)

Question 9

What is problematic about a large cell?

Answer 9

-if a cell gets too large it cannot move nutrients into the cell and move wastes out of the cell efficiently.
-as cells grow, they place increasing demand on their DNA. This means that if there is a genetic error, the cell will die. This is why most organisms are multicellular, consisting of many small cells, because there is a high margin for error.

Question 10

What is the mathematical reason why cells divide?

Answer 10

• larger surface area to volume ratio exhibited in a cell ( as cells are divided their volume is split over more surface area) eliminates cell membrane transport issues and unreasonable demands on the cell’s genetic material. This is because volume increases at a faster rate than surface area( bc volume is meters^3 and surface area is m^2)

Question 11

What happens if cells do not pass the checkpoint between the G1/growth/gap phase and the s-synthesis phase?

Answer 11

the cell cycle stops and the cell will not divide anymore

Question 12

what happens if the cells do not pass the checkpoint between the second gap/growth phase and mitosis?

Answer 12

the cell cycle stops to repair damaged DNA

Question 13

What is the G0 phase (senescence?)

Answer 13

After the G1/S Checkpoint, the cell stops dividing and “retires” until apoptosis

Question 14

what is apoptosis and why does it occur?

Answer 14

programmed cell death brought about by the formation of “suicide” proteins
-occurs for evolutionary/environmental adaptations and to kill a cell with a genetic abnormality.

Question 15

What is mitosis and when does it occur?

Answer 15

-mitosis is the division of hte nucleus and occurs directly after the G2 checkpoint of interphase unless the cell goes into G0 (senescence)

Question 16

What is cytokinesis and when does it occur?

Answer 16

-division of the cytoplasm
-occurs directly after mitosis

Question 17

What is chromatin?

Answer 17

he DNA-protein complex which is packed into the nucleus during interphase

Question 18

How are chromosomes formed?

Answer 18

Chromatin condenses into chromosomes as the cell enters mitosis

Question 19

What are chromatids?

Answer 19

-the two identical (sister) parts ( halves) of a chromosome condensed from chromatin during prophase.

Question 20

What occurs during prophase of mitosis?

Answer 20

genetic material inside the nucleus condenses into sister chromatids that form chromosomes
-the miotic spindle of microtubule begins to form. this helps to separate the duplicated chromosomes

Question 21

What happens to sister chromatids at the end of mitosis?

Answer 21

the chromosomes will have seperated into the two daughter cells

Question 22

what is the miotic spindle and what is it used for?

Answer 22

-the miotic spindle is a network of microtubules that begins forming during the prophase of mitosis, and is used during metaphase ti help separate the duplicated chromosomes

Question 23

what occurs during the metaphase of mitosis?

Answer 23

The sister chromatids align along the metaphase plate with the aid of spindle fibers
- the centromeres of the duplicated chromosomes line up across the metaphase plate

Question 24

what occurs during the anaphase of mitosis?

Answer 24

The spindle fibers pull the sister chromatids in opposite directions towards the opposing poles of the cell
The centromere regions of the sister chromatids separate

Question 25

what occurs during the telophase of mitosis?

Answer 25

Two nuclear envelopes now form around the separated chromosomes at opposite ends of the original cell
Division of the genetic material is now complete

Question 26

what is the final phase of mitosis?

Answer 26

cytokinessis, as the cytoplasm divides into the two cells

Question 27

what are the phases of mitosis in order?

Answer 27

prophase, metaphase, anaphase, telophase, cytokinesis

Question 28

Cytokinesis

Answer 28

he division of the cytoplasm and the cell organelles to complete mitosis

Question 29

at are cancer cells and what are their characteristics?

Answer 29

Abnormal cells dividing without the control of the cellular checks and balances
Cancerous cells have the ability to invade other tissues(metastasis) and consume their resources

Question 30

what happens when mitosis and apoptosis are not in homeostasis

Answer 30

a tumor can form

Question 31

What are the differences between anaphase and telophase?

Answer 31

During anaphase, the sister chromatids have been pulled apart from their centromere regions, but are not at opposite ends of the cell. during telophase, the chromatids are at opposite ends of the cell,and two nuclear envelopes form around this genetic material