Lecture 10

Question 1

What is a genome

Answer 1

All genetic material in a cell

Question 2

What happens to chromatin when it tightly coils around many proteins

Answer 2

It forms a chromosome

Question 3

What does diploid mean

Answer 3

Two complete sets of chromosomes (one from each parent)

Question 4

What is a karyotype

Answer 4

Person’s chromosomes arranged by and numbered by size

Question 5

How many pairs of chromosomes in a somatic cell

Answer 5

23 (46 chromosomes)

Question 6

What is the cell cycle

Answer 6

Time between when a cell forms and divides into 2 daughter cells

Question 7

Stages in cell cycle

Answer 7

Interphase, mitotic phase

Question 8

Phases of interphase

Answer 8

G1, S, G2

Question 9

Which phase of interphase : begins as soon as daughter cell formed, active growth, synthesis of new organelles and reaches mature cell size

Answer 9

G1

Question 10

Which interphase phase : dna replication, exact copy of each chromosome is made

Answer 10

S phase

Question 11

What are sister chromatids

Answer 11

Copied chromosomes, attached to center by centromere

Question 12

Number of chromatids during synthesis phase

Answer 12

92 (sister chromatids each with 46 chromosomes)

Question 13

G2 phase :

Answer 13

2nd growth phase, prep for mitotic phase (centrosomes duplicate and spindle fibres form)

Question 14

Mitosis stages

Answer 14

1. Prophase (early and late)
2. Metaphase
3. Anaphase
4. Telophase

Question 15

What happens during early prophase

Answer 15

Chromatin compacts into chromosomes, nucleus still intact, spindle fibers extend

Question 16

What happens during late prophase

Answer 16

Nuclear membrane breaks down, centrosomes at opposite side of cell, some chromosomes attach to spindles

Question 17

What happens during metaphase

Answer 17

Chromosomes align at cell midline (metaphase plate)

Question 18

What happens during anaphase

Answer 18

Sister chromatids separate, pulled to opposite ends of cell using microtubules as tracks, cell elongates, at the end the cell ends has complete set of chromosomes

Question 19

How are sister chromatids pulled appart during anaphase

Answer 19

Proteins holding them broken down by enzyme

Question 20

What happens during telophase

Answer 20

Chromatine fibers start to loosen up/becomes less coiled, spindles disappear, nuclear membrane forms, nucleoli reappear, end of mitosis

Question 21

Cytokinesis (other stage of mitotic phase)

Answer 21

Cell pinches in half forming a cleavage furrow, results in twi daughters cells w same gene info, begins while still in telophase

Question 22

When dies mitosis occur

Answer 22

Reproduction, growth and development, tissue renewal

Question 23

How do prokaryotic cells divide

Answer 23

Binary fission (circular chromosomes replicate and got to opp ends, plasma membrane pinches at center and divides)

Question 24

Which cell have the same genetic composition

Answer 24

Every somatic cell

Question 25

Every cell in the body has some genes that are turned

Answer 25

Either on or off

Question 26

Cells express different subsets of genes, only expressing those they require which makes each cell

Answer 26

Produce diff types of proteins

Question 27

Cell division length

Answer 27

Actively dividing cells (intestines/skin) : 12h-24h Unicellular organisms : 90min

Question 28

G0 phase :

Answer 28

Pause between M and S phase in cell cycle

Question 29

Examples of cells in G0 phase (liver)

Answer 29

Liver cells remain in it for a year, doing metabolism and detoxification before reentering cell cycle

Question 30

Example of G0 phase cells

Answer 30

Those that form the lens of the eyes and nerve cells perpetually in G0 phase

Question 31

What are checkpoints in cell cycle

Answer 31

When regulatory proteins in cell checks at specific times to make sure everything is ok in cc

Question 32

If something is wrong in cell cycle during checkpoints

Answer 32

Doesn't continue cycle until fixed, if error cannot be fixed -> apoptosis

Question 33

What is apoptosis

Answer 33

Programmed cell death

Question 34

What happens if damaged cell doesn't undergo apoptosis

Answer 34

Keeps dividing, leads to cancer

Question 35

What does cell differentiation mean

Answer 35

When a cell assumes its function in organism, takes in cell-specific characteristics

Question 36

For homeostasis to be maintained, regulatory systems must

Answer 36

Ensure that cells don't divide uncontrollably and differentiate at appropriate time

Question 37

Cancer is when cells

Answer 37

Lose ability to respond to regulatory mechanisms (divide uncontrollably and indefinitely)

Question 38

How can mutations occur

Answer 38

Copying errors in dna replication or induced by exposure to external elements

Question 39

Most affected genes by cancer

Answer 39

Control cell cycle and code for proteins involved in cell division (Those that regulate cell growth and division during cc)

Question 40

What are mutagens

Answer 40

Agent that induces permanent dna change

Question 41

Mutagens example

Answer 41

Radiation (x rays, uv) Chemical (pollutants, metals, tobacco) Biological (viruses and bacteria)

Question 42

What are the twi different cancer stages

Answer 42

Bening and malignant

Question 43

Bening tumors

Answer 43

Mass of cells that don't invade neighbouring tissues (if large enough can impair function of organ, generally encapsulated)

Question 44

Malignant cancer

Answer 44

Mass of cells that invade neighbouring tissues and creates metastasis

Question 45

What is metastasis

Answer 45

Release of cancerous cells into bloodstream or lymph where they can travel and invade other tissues