Lecture 3: Topic 1 Flashcards

1
Q

what are chromosomes made up of

A

DNA and protein

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2
Q

what is chromatin

A

wrapped around protein

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3
Q

are humans diploid or haploid, and why

A

diploid (2n)

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

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4
Q

n (haploid number)

A

23 chromosomes

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5
Q

2n (diploid number)

A

46 chromosomes

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6
Q

characteristic of the two copies of each chromosome in human cells

A

homologous

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7
Q

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

A

alleles

promote different traits (ex. curly or straight hair)

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8
Q

how do cells get the right number of chromosomes

A

through cell division

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

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9
Q

what cell components are duplicated during cell division

A
  • organelles
  • cytoplasm
  • chromosomes
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10
Q

what are the 2 main parts of the cell cycle

A
  • interphase

- cell division

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11
Q

what steps is interphase made up of

A

G1
S
G2

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12
Q

what step is cell division made up of

A

mitosis (M)

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13
Q

what is G1

A

growth

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

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14
Q

what is S phase

A

synthesis

this is when the cell copies all of its DNA

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15
Q

what is G2 phase

A

gap/growth

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

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16
Q

what are the stages of mitosis

A

prophase
metaphase
anaphase
telophase

17
Q

why do diploid organisms need to have specialized sex cells

A

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

18
Q

how many of each chromosome do gametes have

A

one of each

19
Q

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

20
Q

what (in general) does meiosis do

A

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

21
Q

where does sexual reproduction (meiosis) occur

A

the testis or ovaries

22
Q

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

A

the chromosomes do not separate correctly during mitosis or meiosis

23
Q

how does maternal age affect birth issues

A

as maternal age increases, incidences of birth defects increase

24
Q

what is the relationship between nondisjunction and age, and why

A

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

25
what are the 3 different types of down syndrome
trisomy 21 mosaicism translocation
26
trisomy 21
95% of all cases 3 complete copies in all cells
27
mosaicism
1-2% of all cases 3 copies in some but not all cells
28
translocation
3-4% of cases partial copy of chromosome 21 attached to another chromosome
29
how is down syndrome detected
karyotyping
30
what is karyotyping
- isolate chromosomes during fetal cell division | - arrange in pairs according to size
31
aneuploidies
word that means in general having an extra or 1 less than chromosome
32
what percentage of conceptions terminate in spontaneous abortion
20%
33
what percentage of spontaneously aborted fetuses demonstrate some form of chromosomal imbalance
30%
34
large percentage of fetuses demonstrating chromosomal abnormalities are ________
aneuploid
35
monosomies
monosomies are not often found in spontaneously aborted fetuses, which suggests that monosomic gametes may be very functionally impaired
36
diagnostic testing used in genetic counseling
amniocentesis (15-18 weeks) chorionic villus sampling (CVS) performed 10-12 weeks