Lecture 3: Topic 1

Question 1

what are chromosomes made up of

Answer 1

DNA and protein

Question 2

what is chromatin

Answer 2

wrapped around protein

Question 3

are humans diploid or haploid, and why

Answer 3

diploid (2n)

because we get 2 of each chromosome, 1 from each parent

Question 4

n (haploid number)

Answer 4

23 chromosomes

Question 5

2n (diploid number)

Answer 5

46 chromosomes

Question 6

characteristic of the two copies of each chromosome in human cells

Answer 6

homologous

Question 7

what do you call different versions of a gene, and what do these do

Answer 7

alleles

promote different traits (ex. curly or straight hair)

Question 8

how do cells get the right number of chromosomes

Answer 8

through cell division

duplicating the cell components and separating the material into 2 daughter cells

Question 9

what cell components are duplicated during cell division

Answer 9

• organelles
• cytoplasm
• chromosomes

Question 10

what are the 2 main parts of the cell cycle

Answer 10

• interphase

- cell division

Question 11

what steps is interphase made up of

Answer 11

G1
S
G2

Question 12

what step is cell division made up of

Answer 12

mitosis (M)

Question 13

what is G1

Answer 13

growth

the cell grows and increases the volume of its proteins and organelles

Question 14

what is S phase

Answer 14

synthesis

this is when the cell copies all of its DNA

Question 15

what is G2 phase

Answer 15

gap/growth

the cell continues to grow in both its proteins and its DNA

Question 16

what are the stages of mitosis

Answer 16

prophase
metaphase
anaphase
telophase

Question 17

why do diploid organisms need to have specialized sex cells

Answer 17

sex cells (sperm or egg) allow traits to be combined from two organisms

Question 18

how many of each chromosome do gametes have

Answer 18

one of each

Question 19

what is the name of the special type of cell division that gametes require

Answer 19

meiosis

Question 20

what (in general) does meiosis do

Answer 20

takes diploid cells (2n) and divides them into gametes (n)

Question 21

where does sexual reproduction (meiosis) occur

Answer 21

the testis or ovaries

Question 22

how can a cell end up with an incorrect number of chromosomes

Answer 22

the chromosomes do not separate correctly during mitosis or meiosis

Question 23

how does maternal age affect birth issues

Answer 23

as maternal age increases, incidences of birth defects increase

Question 24

what is the relationship between nondisjunction and age, and why

Answer 24

happens more as you age, because bonding of chromosomes gets weaker with age

Question 25

what are the 3 different types of down syndrome

Answer 25

trisomy 21
mosaicism
translocation

Question 26

trisomy 21

Answer 26

95% of all cases

3 complete copies in all cells

Question 27

mosaicism

Answer 27

1-2% of all cases

3 copies in some but not all cells

Question 28

translocation

Answer 28

3-4% of cases

partial copy of chromosome 21 attached to another chromosome

Question 29

how is down syndrome detected

Answer 29

karyotyping

Question 30

what is karyotyping

Answer 30

• isolate chromosomes during fetal cell division

- arrange in pairs according to size

Question 31

aneuploidies

Answer 31

word that means in general having an extra or 1 less than chromosome

Question 32

what percentage of conceptions terminate in spontaneous abortion

Answer 32

20%

Question 33

what percentage of spontaneously aborted fetuses demonstrate some form of chromosomal imbalance

Answer 33

30%

Question 34

large percentage of fetuses demonstrating chromosomal abnormalities are ________

Answer 34

aneuploid

Question 35

monosomies

Answer 35

monosomies are not often found in spontaneously aborted fetuses, which suggests that monosomic gametes may be very functionally impaired

Question 36

diagnostic testing used in genetic counseling

Answer 36

amniocentesis (15-18 weeks)

chorionic villus sampling (CVS) performed 10-12 weeks