lecture 3

Question 1

DNA

Answer 1

is
composed of two
strands winding
around each
other to form a
double helix

Question 2

nucleotide has
three parts

Answer 2

Sugar:
Deoxyribose
Chemical building blocks of DNA
are nucleotides.
2. Phosphate
3. Base containing
Nitrogen
(A, T, C, G)

Question 3

how many chromosomes do humans have (not Dow syndrome)

Answer 3

23

Question 4

23 pairs of chromosomes

Answer 4

 1 of each pair comes from mom and one from dad
 Homologous chromosomes are ones
that:
 Carry the same traits
 Are the same size
 Have the same centromere location Show the same banding pattern

Question 5

Homologous vs nonhomologous

Answer 5

Homologous is same height centrosomes at same level
nonhomologous is not same height and centrosomes different level

Question 6

23rd chromosome

Answer 6

23rd = sex chromosome female =xx
male = XY
dad gives X or Y mom only gives X

Question 7

Do all cells divide at the same rate?

Answer 7

Some cells are damaged quite often and need to be replaced quickly.
 Stomach lining
 Skin
 Blood
 Other cells rarely if ever divide.
 Nerve cells
 Cardiac (heart) cells

Question 8

cell cycle

Answer 8

. DNA in the nucleus must be copied2. Each copy must be moved into a
separate new cell (daughter cells)
3. Original cell must divide in half to form
the two new daughter cells

Question 9

Interphase

Answer 9

Dna is copied

Question 10

mitosis

Answer 10

Dna is split equally into to daughter cells

Question 11

cytokinesis

Answer 11

parent cell is cleaved in half

Question 12

Chromatin

Answer 12

Uncondensed
DNA that
normally exists
in the nucleus.

Question 13

Chromosomes

Answer 13

Condensed, more ordered DNA.
Visible under the microscope.

Question 14

Sister Chromatids

Answer 14

copied
chromosomes that are still connected
to each other. One is needed for each daughter cell.

Question 15

 Centromere

Answer 15

: The site of attachment for the two sister chromatids.

Question 16

The Steps of the Cell
Cycle

Answer 16

. Interphase
2. Prophase
3. Metaphase
4. Anaphase
5. Telophase
6. Cytokinesis

Question 17

Interphase

Answer 17

Longest phase of the cell’s life
 Cell performs its required functions,
whatever the cell’s normal job is.
 Three phases
1. G1
2. S
3. G2

Question 18

G1 (Gap 1)

Answer 18

Cell’s organelles are duplicated Cell grows larger

Question 19

S Phase (Synthesis)

Answer 19

 Chromosomes are replicated (copies)
 This makes a copy for each of the cells
that result from mitosis.
 Each copy of the chromosome is called a sister chromatid. (they are not visible yet)

Question 20

G2 (Gap 2)

Answer 20

Cell prepares for division
 Proteins that are required for mitosis are produced

Question 21

Mitosis

Answer 21

Division of somatic cells.

Question 22

Somatic cells

Answer 22

any cells in the body
EXCEPT for sex cells

Question 23

end of mitosis

Answer 23

two genetically
identical daughter cells are produced.

Question 24

4 phases

Answer 24

Prophase, Metaphase,
Anaphase, and Telophase.

Question 25

Prophase

Answer 25

Longest phase of cell division

Question 26

Chromatin (Prophase)

Answer 26

condenses into chromosomes
which are now visible under the microscope.

Question 27

 Microtubules (Prophase)

Answer 27

called the spindle, begin to grow from the centrioles

Question 28

Nuclear membrane (Prophase)

Answer 28

dissolves so chromosomes can move around the cell freely.

Question 29

Centrioles (Prophase)

Answer 29

anchor the spindle at the poles
(opposite sides) of the ready-to-divide cell.

Question 30

Metaphase

Answer 30

Chromosomes line up single file across
the “equator” of the cell
 Spindle is attaches to each duplicated
chromosome at the centromere.
 Think of MIDDLE when you think
METAPHASE.

Question 31

Anaphase

Answer 31

Sister chromatids are separated from
each other.
 Spindle shortens to “pull” chromosomes
towards the poles of the cell.

Question 32

Telophase

Answer 32

Nuclear envelope reforms around the
chromosomes at each pole.
 Chromosomes may begin to unwind back into chromatin.
 Cell membrane begins to “pinch in” at the middle.

Question 33

Cytokinesis

Answer 33

Means “cellular movement”
 Cytoplasm is divided in half to form two
genetically identical daughter cells.
 Two new cells start back at Interphase.

Question 34

Tumor

Answer 34

: Mass of cells that has no function

Question 35

Benign

Answer 35

tumors that stay in one place

Question 36

Malignant

Answer 36

: tumors that invade other
neighboring tissues. These are cancerous.

Question 37

Metastasis

Answer 37

When cancer cells break away
from an original tumor and create another
tumor elsewhere in the body

Question 38

How are cancer cells
different from normal cells?

Answer 38

. They divide when they should not
2. They invade surrounding tissues
3. They move to other locations in the
body

Question 39

small cells move around the body during cancer?

Answer 39

They travel via the lymphatic and the circulatory systems.

Question 40

Circulatory System

Answer 40

The circulatory system includes
the heart, blood, and blood
vessels.

The smallest blood vessels are
capillaries.

Question 41

Lymphatic System

Answer 41

 When nutrients move from the blood into the tissues, fluid is lost from the capillaries.
 This extra fluid is called lymph.
 The lymphatic system collects this
liquid and returns it to the circulatory system.

Question 42

Why are lymph nodes removed to diagnose and assess cancer?

Answer 42

Lymph nodes are small ducts that filter
the lymph using white blood cells.
 If abnormal cells are in the lymph, most
likely they are moving around the body.

Question 43

Why do cells need to
divide?

Answer 43

 Heal wounds
 Replace damaged cells
 Growth

Question 44

How is the cell cycle
controlled?

Answer 44

There are checkpoints the cell must pass through before it can divide.
 Proteins check to make sure conditions
are right for the cell to divide

Question 45

where are check points

Answer 45

The first checkpoint is
between G1 and S

Question 46

Proteins check to make sure

Answer 46

. The cell is large enough to divide
2. Nutrients are available
3. Growth Factors (proteins) must be
present for the cell to divide.

Question 47

Second checkpoint is at G2

Answer 47

This checkpoint ensures that the DNA
was replicated properly.
 Cell size is checked again

Question 48

Final Checkpoint =
Metaphase

Answer 48

 Proteins verify that all of the
chromosomes are attached so that cell
division can proceed properly.
 IF PROTEINS DURING ANY OF THE
CHECKPOINTS FIND A PROBLEM,
CELL DIVISION IS STOPPED!

Question 49

Oncogenes

Answer 49

are cancer causing genes
that stimulate cell division even if there
are no signals (growth factors) present.

Question 50

Cancer cells do not exhibit contact
inhibition

Answer 50

contact
inhibition which normally prevents cells from growing on top of each other.

Question 51

Biopsy

Answer 51

the removal of cells, tissue, or
fluid to determine if they are cancerous

Question 52

Haploid

Answer 52

cells (n) contain only one
chromosome from each homologous pair.
 Think of haploid as “half” the total number of
chromosomes

Question 53

Diploid

Answer 53

cells (2n) have both members of a pair of homologous chromosomes
 Diploid cells have “double” the haploid number of chromosomes - the one from your mom andthe one from your dad

Question 54

Overview of meiosis

Answer 54

Similar to mitosis in that it has similar
phases: Interphase, Prophase,
Metaphase, Anaphase, Telophase.
 In Meiosis, however, these phases occur twice so you have:
 Meiosis I
 Meiosis II

Question 55

Helicase

Answer 55

is the name of the enzyme that unzips the molecule

Question 56

DNA polymerase

Answer 56

is the name of the enzyme that adds free nucleotides

Question 57

Meiosis I

Answer 57

Has same steps as mitosis
 Prophase I
 Metaphase I
 Anaphase I
 Telophase I