Bioquest 9

Question 1

Chromosomes

Answer 1

rod shaped structures made of DNA and proteins. DNA is coiled (during cell division)- one DNA coils around protiens (histones)

Question 2

Histones

Answer 2

proteins in eukaryotic chromosomes (DNA wraps tightly around them)- help maintain the structure of the chromosome and aids with the tight packing of DNA

Question 3

nonhistones

Answer 3

proteins that are generaly involved in controlling the activity of specific regions of the DNA

Question 4

chromatid

Answer 4

each identical half of a chromosome- form as the DNA makes a copy of itself before cell division (each of the two new cells receives one)

Question 5

centromere

Answer 5

the point where the two chromatids of a chromosome are attached

Question 6

chromatin

Answer 6

the state of DNA in-between division (not so tightly coiled (less tightly coiled DNA-protein complex)

Question 7

Prokaryotic chromosomes

Answer 7

much simpler- DNA consists of only 1 chromosome which is attached to the inside of the cell membrane. Prokaryotic chromosomes consist of a circular DNA molecule.

Question 8

sex chromosomes

Answer 8

chromosomes that determine the sex of an organism- in humans sex chromosomes are either X or Y- females normally have two X chromosomes and males normally have an X and Y chromosome (humans have 2)

Question 9

autosomes

Answer 9

all other chromosomes that are not sex chromosomes (humans have 44)

Question 10

homologous chromosomes

Answer 10

the two copies of each autosome (one autosome from each parent)- they are the same size and shape and carry the same genes for the same traits

Question 11

diploid cell

Answer 11

cells with two sets of chromosomes

Question 12

haploid cells

Answer 12

(ie sperma and egg cells)- contain only one set of chromosomes (one autosome in each pair and one sex chromosome = 23 total)

Question 13

cell division in prokaryotes

Answer 13

binary fission- DNA is copied, cell begins to divide, cell completely divides resulting in two identical haploid cells

Question 14

Cell division in eukaryotes (two types)

Answer 14

mitosis and meiosis

Question 15

mitosis

Answer 15

results in new cells with genetic materiel that is identical to the genetic material of the original cell

Question 16

meiosis

Answer 16

occurs during the formation of gametes (haploid reproductive cells)- it reduces the chromosome # by half in new cells. each cell can join with another haploid cell to produce a diploid cell with a complete set of chromosomes

Question 17

the cell cycle

Answer 17

the repeating set of events in the life of a cell- includes interphase, mitosis and cytokenisis

Question 18

interphase

Answer 18

G1: offspring cells grow to mature size, S: DNA is copied (synthesized), G2: prepares for cell division

Question 19

stages of mitosis:

Answer 19

prophase, metaphase, anaphase, telophase/cytokenisis

Question 20

prophase

Answer 20

1) shortening and coiling of DNA into rod shaped chromosomes 2) nucleolus and nuclear membrane break down and dissapear 3) centrosomes appear and move towards opposite poles of cell 4) spindle fibers (made of microtubules) radiate from centrosomes (mitotic spindle- made of kinetochore and polar fibers)

Question 21

metaphase

Answer 21

kinetochore fibers move the chromosomes to the center of the cell and hold them in place

Question 22

anaphase

Answer 22

the chromatids of each chromosome separate and the centromere and move towards opposite poles (now each considered chromosomes)

Question 23

telophase

Answer 23

after the chromosomes reach opposite sides of the cell the spindle fibers disassemble and the chromosomes return to chromatin state. then a nuclear envelope forms around each set of chromosomes and a nucleolus forms in each of the newly forming cells

Question 24

cytokenisis in animal cells

Answer 24

cytoplasm divides- pinching inward of cell membrane creating a cleavage furrow. it eventually separates

Question 25

cytokenisis in plant cells

Answer 25

vesicles from golgi join at midline of cell forming a cell plate-a wall forms and divides into two cells