8- Mitosis and the Cell Cycle

Question 1

What is gene expression?

Answer 1

the process by which DNA directs protein synthesis to determine our traits

Question 2

Why do living organisms need cell division? (3)

Answer 2

• Reproduction: creating a new organism (offspring)
• Growth and Development: Get bigger and mature into an adult
• Replace: old and damaged cells to maintain healthy tissues

Question 3

What is binary fission?

Answer 3

Cell division resulting in 2 organisms

Question 4

What form of reproduction is binary fission?

Answer 4

asexual

Question 5

How do single celled eukaryotes go through binary fission?

Answer 5

mitosis

Question 6

How does binary fission by prokaryotes function?

Answer 6

• The single loop of DNA is replicated from a starting point (origin) in both directions moving towards opposite ends of the cell
• Cell elongates during DNA replication
• Plasma membrane pinches in the middle to separate the 2 daughter cells

Question 7

What is the purpose of mitosis?

Answer 7

responsible for growth, development and replacement of old and damaged cells in multicellular

Question 8

What is the purpose of meiosis?

Answer 8

responsible for creating gametes (sperm and eggs) for sexual reproduction

Question 9

How are chromosomes and chromatin packaged?

Answer 9

• Chromosomes: DNA during cell division –> chromatin tightly coiled around proteins
• Chromatin: DNA when cell is not dividing –> long thin threads

Question 10

What are the 2 basic cell types based on the number of chromosomes they contain in the human body?

Answer 10

1) Somatic cells (body cells)
2) Gametes (sex cells; eggs and sperm)

Question 11

What are somatic cells? How many chromosomes do they have?

Answer 11

• All of the cells that make up the tissues of our bodies
• Have 46 chromosomes (2 two set of 23 unique chromosomes, one set from each parent)

Question 12

What are gametes cells? How many chromosomes do they have?

Answer 12

• Specialized reproductive cells, eggs and sperm
• Have only 23 chromosomes

Question 13

What is a karyotype? How are the chromosomes arranged?

Answer 13

an organized profile of an organism’s chromosomes where they are arranged in pairs from largest to smallest in size

Question 14

What is a karyotype? How are the chromosomes arranged?

Answer 14

an organized profile of an organism’s chromosomes where they are arranged in pairs from largest to smallest in size

Question 15

What are autosomal chromosomes? How many pair do humans have?

Answer 15

all chromosomes that are not related to sex determination are autosomal chromosomes
- humans have 22 pairs

Question 16

What are sex chromosomes and have do they differentiate between male and female in humans?

Answer 16

• chromosomes involved in sex determination
• In humans, males have 2 different sex chromosomes (XY) and females have 2 same sex chromosome (XX)

Question 17

What is karyotyping used for?

Answer 17

diagnose genetic disorders

Question 18

What is a zygote?

Answer 18

the new cell formed after one sperm cell enters the egg cell and their nuclei fuse together forming one nucleus containing both sets of chromosomes

Question 19

How does a zygote grow?

Answer 19

grows by increasing its number of cells through repeated cell divisions

Question 20

How is the original genetic information of zygotes copied?

Answer 20

it is copied exactly before each cell division, ensuring that all new cells have a complete copy of all the chromosomes

Question 21

What is mitosis?

Answer 21

Cell division creating 2 daughter cells with identical copies of the original components

Question 22

Why do certain somatic cells undergo mitosis?

Answer 22

to regenerate damaged or old tissues others when we are growing and developing

Question 23

What type of cell division will most cells in our body undergo?

Answer 23

most cells will never undergo a mitotic cell division

Question 24

What type of certain specialized cells undergo mitosis repeatedly?

Answer 24

stem cells

Question 25

What is G0?

Answer 25

when a cell is not going to progress into cell division

Question 26

What is the cell cycle?

Answer 26

Time between when a cell is created and the time it divides creating 2 new daughter cells

Question 27

What are the 2 phases of the cell cycle?

Answer 27

1. interphase 2. mitotic phase

Question 28

What is the difference between interphase and mitotic phase regarding the length and function?

Answer 28

1. Interphase - Long phase - Cell growth - DNA replication 2. Mitotic phase - Short phase - Division of replicated chromosomes equally into 2 daughter cells

Question 29

What are the 3 distinct stages interphase?

Answer 29

1. growth 1 2. synthesis (S) 3. growth 2

Question 30

When does growth 1 begin?

Answer 30

as soon as daughter cells are formed

Question 31

What type of period is growth 1?

Answer 31

of active growth

Question 32

What happens during growth 1?

Answer 32

cell increases in size - extensive synthesis of new organelles that eventually reach mature size

Question 33

What happens to cells that will not divide during growth 1?

Answer 33

complete this stage of the cell cycle and then stop in G0

Question 34

What type of cells progress to the synthesis stage?

Answer 34

cells destined to divide

Question 35

What happens drying the synthesis stage?

Answer 35

exact copy of each chromosome is made

Question 36

What happens to each new copy of a chromosome during the synthesis stage? What is it now called?

Answer 36

remains attached to the original and is now called a replicated chromosome

Question 37

When DNA is replicated in the synthesis stage, what form is it in and when does its form change?

Answer 37

it is in chromatin form and does not condense into chromosomes until mitosis begins

Question 38

What is a replicated chromosome?

Answer 38

identical copies of a chromosome that remain attached at the centromere

Question 39

What is each new copy of a chromosome referred to after it is replicated in the synthesis stage?

Answer 39

chromatid

Question 40

When does a chromosome start being referred to as a chromatid during the cell cycle?

Answer 40

after it is replicated in the synthesis stage

Question 41

What is the difference between sister chromatids and non-sister chromatids?

Answer 41

- Sister chromatids: identical chromatids attached by a centromere - Non-sister chromatids: Chromatids are not attached by a centromere (on different replicated chromosomes)

Question 42

What happens during growth 2?

Answer 42

cell continues to grow and prepares for the mitotic phase by replicating the centrosome

Question 43

What begins to form during growth 2?

Answer 43

spindle fibers

Question 44

What does the cell have at the end of the growth 2 stage?

Answer 44

- Replicated chromosomes - Two centrosomes - Spindle fibers forming

Question 45

What is the purpose of the mitotic phase of mitosis?

Answer 45

Sees the sorting and equal distribution of the replicated chromosomes into 2 new daughters

Question 46

What are the 2 steps of the mitotic phase?

Answer 46

1. mitosis 2. cytokenesis

Question 47

What are the 4 distinct stages of mitosis?

Answer 47

- Prophase - Metaphase - Anaphase - Telephone

Question 48

What happens during prophase of mitosis concerning the chromatin, centrosomes, nuclear envelope and spindle fibres?

Answer 48

- Chromatin condenses into chromosomes - Centrosomes migrate to opposite ends (poles) of the cell - Nuclear envelope breaks down - Spindle fibers extend out from the centrosomes into the middle of the cell where the chromosomes are and attach to their centromeres

Question 49

What happens during metaphase of mitosis?

Answer 49

- Replicated chromosomes align on the cell’s midline (metaphase plate) with one sister chromatid on either side

Question 50

How are replicated chromosomes attached during metaphase of mitosis?

Answer 50

- Each replicated chromosome is attached at their centromere (kinetochore proteins) by spindle fibers which extend from both centrosomes

Question 51

What happens to the sister chromatids during anaphase of mitosis?

Answer 51

spindle fibers pull sister chromatids apart at their centromeres and they are pulled to opposite poles of the cell

Question 52

What happens to the cell during anaphase of mitosis?

Answer 52

cell elongates

Question 53

What does each pole have at the end of anaphase of mitosis?

Answer 53

each pole has 1 copy of every chromosome that existed in the parent cell

Question 54

What happens during telophase of mitosis concerning the chromosomes, nuclear membrane and spindle fibres?

Answer 54

- Chromosomes amass at each pole and begin to loosen - Nuclear membranes form around each group of chromosomes - Spindle fibers break down

Question 55

What is cytokinesis?

Answer 55

Division of the original cell into two daughter cells

Question 56

What happens during cytokinesis?

Answer 56

Parent cell pinches around its midline until 2 new cells are made

Question 57

When does cytokinesis occur?

Answer 57

same time as telophase

Question 58

How does cytokinesis happen in plant cells?

Answer 58

daughter cells are separated by the growth of a cell plate in between them that becomes the new cell wall

Question 59

What type of cells are produced after the mitotic phase and the cell cycle?

Answer 59

2 daughter cells genetically identical to the parent cell

Question 60

What happens to the new daughter cell created after the mitotic phase of the cell cycle

Answer 60

new daughter cells now enter the G1 phase of the cell cycle