Lecture--Chapter 2

Question 1

Most of the time, a cell is in the __ or __ phase:

Answer 1

G1 or G2

Question 2

G1 phase:

Answer 2

growth

Question 3

G2 phase:

Answer 3

metabolism

Question 4

The proportion of time that a cell spends in mitosis is:

Answer 4

1/10 of the typical cell cycle time

Question 5

What is interphase?

Answer 5

The portion of the cell cycle that occurs between division events.

Question 6

What are the 4 stages of mitosis?

Answer 6

1. prophase
2. metaphase
3. anaphase
4. telophase

Question 7

What happens during prophase?

Answer 7

The nuclear membrane dissolves and the DNA condenses from loose coils into tight coils with identical chromatids joined at the centromere.

Question 8

What is a chromatid?

Answer 8

One of the two identical copies of DNA making up a duplicated chromosome.

Question 9

What happens during metaphase?

Answer 9

The chromosomes attach at their centromeres to the microtubules of the mitotic spindle and are positioned mid-planar within the cell.

Question 10

What is the mitotic spindle?

Answer 10

A network of protein filaments that are attached at opposite poles of the cell, which moves and positions chromatids.

Question 11

What is the centromere?

Answer 11

The region of DNA that occurs typically near the middle of a chromosome where two identical sister chromatids come closest in contact.

Question 12

What happens during anaphase?

Answer 12

The sister chromatids are separated and moved to the opposite poles of the cell.

Question 13

What happens during telophase?

Answer 13

The nuclear envelope reforms, the chromatin reappears in the nucleoli as the DNA uncoils and it compacted with histones and other proteins.

Question 14

What happens after telophase?

Answer 14

cytokinesis

Question 15

Magnification:

Answer 15

refers to the apparent increase in object size. The maximum magnification is reached when the finest detail an instrument can resolve with the given objectives matches the finest detail the eye can see.

Question 16

Further enlargement of magnification beyond the limit of the finest detail the eye can see is:

Answer 16

empty magnification–results in a cloudy image

Question 17

Define resolution:

Answer 17

the ability to distinguish objects that are close together–related to viewing distance, but it depends ultimately on the wavelength of light used for imaging and the numerical aperture of the lens.

Question 18

numerical aperture of the lens:

Answer 18

the ability of the lens to gather light

Question 19

Define contrast:

Answer 19

helps determine resolution by providing different optical intensities of the sample relative to its background

Question 20

Define refraction:

Answer 20

light bending as it passes through glass

Question 21

With a lens that has a shorter focal length:

Answer 21

the optical power is greater

Question 22

Magnification depends on:

Answer 22

focal length and the distance from an objective to the eye piece (tube length).