Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology🧪🌱💦 > Lecture 9 > Flashcards

Lecture 9 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Little recap from chapter 8:
How many Stages of Cell Cycle + name them

A

2 Stages of Cell Cycle:
1) Interphase
2) Mitotic phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Name the 3 main things that happen in Interphase

A

G1 -normal growth
S -chromosomes copied (synthesis)
G2 -final growth/preparation for division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Little explanation of what happens in the mitotic phase:

A

4 steps: Prophase, Metaphase, Anaphase and Telophase (PMAT)
- distribution of chromosomes
- each daughter cell gets an EXACT COPY of the parent cell’s chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is truly the last step but is not included in mitosis?

A

cytokinesis (separation of the 2 daughter cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an asexual reproduction?

A

organisms reproduce offspring that are EXACT copies of themselves
+ A single individual is the SOLE parent to donate all of its genes to its offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a sexual reproduction?

A

2 parents produce offspring (that have unique combinations of genes inherited from the 2 parents)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Through sexual reproduction, does it vary genetically or are they clones?

A

SEXUAL: vary genetically
Asexual: clones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do humans reproduce?

A

by sexual reproduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

In humans, how many chromosomes does each somatic cell have?

A

46 chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are somatic cells?

A

all cells other than sperm and ovum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many chromosomes do our sex cells (sperm & eggs) have?

A

they have 23 chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does mitosis ensure?

A

Ensures that each daughter cell gets an EXACT COPY of the genetic information from
parent cell (Daughter cells are clones of original parental cell)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

TRUE OR FALSE:
In a sexual reproduction, the offspring are identical to the
parents.

A

FALSE, they are not identical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What cycle do we use to produce gametes?

A

we use MEIOSIS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How different are they?

A
  • differ genetically from the parents
  • and also from each other
    (all genetically different)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Meiosis (sex-cell formation) occurs in cells that will become what?

A

that will become gamete cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What produces sperm in males?

A

spermatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Spermatocytes produce sperm via what?

A

meiosis
(product (sperm) are all genetically different)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how are spermatocytes produced?

A

Through mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What will produce eggs in females?

A

primary oocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

the eggs are produced from primary oocytes via what?

A

meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are the primary oocytes produced?

A

by mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Meiosis produces cells that:
(2 important factors)

A

1) have ½ the # of chromosomes found in the original parent cell
2) are genetically different from parent cells (& each other)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why halve chromosomes #?

A

human cells contain 46 chromosomes
if chromosome # is not halved, then egg with 46 + sperm with 46
will make a child with 92
then 92 + 92 = 184 ….
(so # of chromosomes would double)
therefore, meiosis keeps chromosome# CONSTANT (b/w each new generation (offspring))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How are there 23 pairs? how much from each parent?

A

1 complete set of 23 chromosomes from mom
1 complete set of 23 chromosomes from dad
23 + 23 = 46 TOTAL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In a human somatic cell, there are 46 chromosomes
1) how many pairs?

A

23 homologous Pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Difference b/w diploid and haploid cells?

A

Diploid: cells with 2 sets of chromosomes
Haploid: cells with 1 set of chromosomes

So Diploid = 2Haploid
N = 2N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Are homologous pairs of chromosomes identical?

A

No, not identical, just similar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Finish the sentence:
Homologous chromosomes code
for the _____ _____

A

for the same genes

So basically homologous regions code for the same gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

These same genes, do they have different or identical alleles?

A

DIFFERENT ALLELES (different versions of that gene
(brown vs blue))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are alleles?

A

an alternative version of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Give an example of an allele

A

the gene for flower color in
pea plants exist in 2 versions:
– 1 for purple flowers and the
other for white flowers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Do alleles control the same character or different?

A

The same character BUT do not necessarily contain the same info (purple vs blue)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the 2 major genes for eye color?

A

one that controls for brown or blue

one that controls for green or hazel

other genes modify the above genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

LET’S DO A QUICK RECAP ON ALL OF THIS

A

(to understand the main components of what meiosis is (w/o the steps))

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q
  1. # of chromosomes in a somatic cell
  2. how many pairs of chromosomes?
  3. Arranged in sets of how many?
A
  1. 46
  2. 23 pairs
  3. sets of 2 (1 mom + 1 dad)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What does the offspring get?

A

only one set from each parent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Goal of meiosis

A

convert diploid parent cells in the ovary/testis into haploid sex cells

39
Q

Which one is a longer process (meiosis or mitosis)?

A

meiosis

40
Q

how much time on average does a somatic cell mitosis happen?

A

12-24 hours

41
Q

How much time for meiosis?

A

> 48 days

42
Q

How many division cycles does meiosis have?

A

2 division cycles

43
Q

What is the result after Meiosis I?

A

results in 2 daughter cells

44
Q

What is the result after Meiosis II?

A

results in 4 daughter cells

45
Q

What is smt important to note b/w meiosis I and II?

A

after the cytokinesis in meiosis I, there is NO FURTHER DNA REPLICATION
so NO interphase
(go directly to Meiosis II, do not pass thru Interphase, do not replicate DNA)

46
Q

Name all the steps in Meiosis I

A

Prophase I
Metaphase I
Anaphase I
Telophase I

Cytokinesis (2 daughter cells)

47
Q

Name all the steps in Meiosis II

A

Prophase II
Metaphase II
Anaphase II
Telophase II

Cytokinesis (4 daughter cells)

48
Q

Like mitosis, meiosis 1 is preceded by interphase, what happens during this phase?

A

G1 phase, S phase, G2 phase
 duplication of chromosomes
 2 chromatids held together by centromeres
 centrioles also replicate (form centrosome)

49
Q

What happens in Prophase I?

A

(similar to mitosis)
NND/SAK/CS
NND: Nucleolus and Nuclear membrane disappear
SAK: Spindle attached to kinetochore
CS: Centrioles continue sperating

50
Q

What is different than mitosis?

A

The homologous pairs LINE UP with other homologous pairs

51
Q

This line up with other homologous pairs forms what?

A

Tetrads

52
Q

So what happens in Prophase I?

A

the formation of Tetrads (homologous chromosomes pair up)

53
Q

What is called the process where homologous chromosomes come together is?

A

Synapsis (a process where a pair of homologous chromosomes held tightly together by proteins & CROSSING OVER occurs)

54
Q

What does crossing-over produce?

A

it produced new gene combinations

55
Q

TRUE OR FALSE: paired homologous chromosomes exchange genetic material between sister chromatids

A

FALSE:
b/w NON sister chromatids

56
Q

What does this mean?

A

chromatid from mom crosses over with chromatid from dad
–> chromatid from mom does NOT cross over with sister chromatid from mom

57
Q

So what is crossing-over?

A

Exchange of genetic material with an equivalent part of a
chromatid from the other homologous chromosome
(mom & dad, not mom & mom)

58
Q

Crossing-over occurs during what phase?

A

Prophase I

59
Q

What is the end result?

A

the chromosomes will have the same number of genes but the sister chromatids are NO LONGER IDENTICAL
(+ contain parts from BOTH mom& dad now)
(+ different alleles)

60
Q

TRUE OR FALSE: Crossing over occurs at a specific point on a chromosome.

A

FALSE
it can occur at any point

61
Q

Why is this great?

A

b/c it introduces variation

62
Q

Let’s recap, what happens during Prophase I?

A

(similar to mitosis)
NND/SAK/CS/HPT
NND: Nucleolus and Nuclear membrane disappear
SAK: Spindle attached to kinetochore
CS: Centrioles continue separating
HPT: Homologous pairs line up forming Tetrads

63
Q

What comes after Prophase I?

A

Metaphase I

64
Q

What happens during Metaphase I?

A

Spindles move Tetrads to cell midline (metaphase plate)
Tetrads -> line up as homologous pairs (4 chromatids, NOT as 2 identical sister chromatids)

65
Q

State the main difference between Metaphase in Mitosis and Metaphase I in meiosis

A

Metaphase Mitosis:
- line up in a single file (kinetochores are attached to opposite poles of a single chromosome (2 sister chromatids)

Metaphase I Meiosis:
- chromosome line up as homologous pairs (TETRADS)

66
Q

What happens during Anaphase I?

A

Homologous pairs segregate (set apart/split up)

67
Q

Are the chromatids attached or separated?

A

Chromatids remain
attached!

68
Q

What does this mean then? Homologous pairs segregate

A

– Both copies of a homologous
pair go to one end of cell
– Both copies of the other go to
the opposite end

69
Q

State the main difference between Anaphase in Mitosis and Anaphase I in meiosis

A

Anaphase Mitosis:
Centromere breaks sister chromatids separated (+ Each pole gets 1 copy of each single chromosome (1 sister chromatid) The daughter cell remains Diploid (2n) Has 2 different chromosomes)

Anaphase I Meiosis:
Homologous chromosomes separate this is called segregation Each pole gets 1 double / replicated chromosome (pair of chromatids) Diploid  haploid (n) Has 1 chromosome only

70
Q

What comes after Anaphase I?

A

Telophase I

71
Q

Name all the 4 things that happen during Telophase I:

A

COE, CAC, NMC, NR
COE: chromosomes drawn to opposite ends of cell
CAC: chromatids still attached by centromeres
NMC: nuclear membrane surrounds chromosomes
NR: Nucleoli reappear

72
Q

What comes after Telophase I?

A

Cytokinesis

73
Q

What is the result after cytokinesis?

A

Each daughter cell has both copies of one of each kind of
chromosome
(Reduced from 2n to n at this point => daughter cells are haploid & genetically different)

74
Q

What is the conclusion at the end of Meiosis I?

A

Have 2 daughter cells (genetically different)
- CHROMOSOME # IS HALVED (1n )!

75
Q

Is there a DNA replication b/w the end of meiosis I and the beginning of meiosis II?

A

NO, CHROMOSOME REPLICATION

76
Q

Main result/objective for meiosis II:

A

to distribute the copies of each chromosome into separate cells
= separate sister chromatids

77
Q

Name all the steps for meiosis II

A

Prophase II
– Metaphase II
– Anaphase II
– Telophase II

with cytokinesis at the end

78
Q

Can we say that meiosis II and mitosis are similar?

A

YES, Meiosis II is very similar to Mitosis (without interphase / DNA replication)

79
Q

Name all 3 things happening in Prophase II

A

NMND/SAK/CDS
NMND: Nuclear membrane & nucleoli disappear
SAK: Spindles attach to kinetochore
CDS: Centrosomes duplicate and separate

80
Q

What happens in Metaphase II

A
  • attached chromatids ( ) line up on the midline of cell
81
Q

Are the sister chromatids identical? why?

A

NOT IDENTICAL b/c of the crossing over in Prophase I

82
Q

What happens in Anaphase II?

A
  • centromeres break
  • chromosomes are drawn to opposite ends of the cell
83
Q

What happens in Telophase II?

A
  • Chromosomes are drawn to opposite ends of the cell
    – Nuclear membrane & nucleoli form
84
Q

RESULT of Cytokinesis at the end

A

Each cell divides giving a total of 4

(4 haploid daughter cells genetically unique!!)

85
Q

How many chromosomes does each cell have?

A

– Each cell now has 1 chromosome rather than the 2 the original cell had
(Original parent cell = 2n
Each Daughter cell = n)

86
Q

general questions:
Does mitosis or Meiosis increase genetic variation?

A

Meiosis

87
Q

Name 3 mechanisms that contribute to genetic variation

A
  1. Crossing over (during prophase
  2. Independent assortment of chromosomes (during metaphase 3. Random fertilization (during zygote formation/conception)
88
Q

Why does Crossing over help with genetic variation?

A

b/c it produces recombinant
chromosomes (combines genes inherited from each parent)

89
Q

How does an Independent assortment of chromosomes help with genetic variation?

A

Each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs in meiosis I
(Fun fact: For humans, there are
more than 8.4 million
possible combinations
of chromosomes)

90
Q

How does Random Fertilization help with genetic variation?

A
  • any sperm can fuse with any ovum (unfertilized egg)
91
Q

What is Evolutionary Significance?

A

Populations evolve through
differential reproductive success of its variant members

92
Q

Why is natural selection important?

A

Natural selection results in the
accumulation of genetic variations
favored by the environment
+ (Different combinations of alleles (sex) may work better than others in certain environments)

93
Q

Difference b/w Mutation and sexual reproduction?

A

Mutation = original source of different alleles
AND
SEXUAL Reproduction= alleles mixed &
matched during meiosis

Biology🧪🌱💦 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions