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A&P : Unit 1 > Chapter 4.1 : DNA Replication & The Cell Cycle > Flashcards

Chapter 4.1 : DNA Replication & The Cell Cycle Flashcards

1
Q

Two type of cell division occur in human physiology :

A

mitosis and meiosis

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2
Q

Mitosis

A

conserves chromosome number (humans = 46)

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3
Q

Human ____ divide by mitosis

A

“somatic cells”

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4
Q

Another name for somatic cells

A

diploid cells

they have 46 chromosomes

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5
Q

Humans have 23 pairs of chromosomes /// total of __
chromosomes

A

46

– 23 came from our mother
– 23 came from our father

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6
Q

karyotype

A

an individual’s complete set of chromosomes

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7
Q

Typical karyotype of somatic cell has twenty-two ____
chromosomes and one pair of __ chromosomes

A

autosome ; sex

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8
Q

Meiosis

A

cell division that reduces chromosome number by ½

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9
Q

gonadal tissue

A

produce gametes by meiosis

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10
Q

Gametes are

A

haploid cells

these are different than our somatic cells in that they only have 23 chromosomes

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11
Q

An egg and a sperm combine their chromosomes to
create a new diploid cell called the ___

A

zygote

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12
Q

Genus species are defined by the
number of ______

A

chromosomes

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13
Q

The number of genes is just an index
of how many different ____ the
species is able to make.

A

proteins

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14
Q

Humans have _chromosomes.

A

46

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15
Q

A rice plant has how many chromosomes?

A

12

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16
Q

Each species of plants and
animals has a set number of
_____

A

chromosomes

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17
Q

In mitosis the cell cycle has two phases

A

interphase and mitotic phase.

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18
Q

Before a cells divides by mitosis, the cell must first

A

double the DNA (the genetic material) // make copy of all the chromosomes

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19
Q

During interphase, DNA’s chromosomes are organized as uncoiled strands called ____ // humans have __ of these strands

A

chromatin ; 46

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20
Q

Parent cell (i.e. the original cell) must double its DNA now the parent cell can give each new cell (the daughter cell) a complete copy of DNA (the chromosomes). What does this occur in and what will be the total number of chromosomes in each daughter cell?

A

This occurs in mitosis // 46 x 2 = 92 (or 46 identical chromosomal pairs)

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21
Q

Law of Complementary Base Pairing

A

we can predict the base sequence of one DNA strand if we
know the sequence of the other

enables a cell to reproduce one strand based on the information
in another

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22
Q

Law of Semi-Conservative Replication

A

New cell will contain DNA molecule with one side new nucleotides and the other side of the DNA molecule will have
“half” of the original DNA molecule

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23
Q

DNA is a ____ constructed by two strands of ____ connected by _____.

A

macromolecule ; nucleic acid ; hydrogen bonds

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24
Q

These four nucleotide molecules are used to make a strand of DNA:

A

Adenine, thymine, guanine, and cytosine

They are paired as:

A+T & G+C

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25
Q

If you have only a single
strand of nucleic acids and
an assortment of
nucleotides, then they will

A

hydrogen bond with their
appropriate nucleotide to
make a new strand

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26
Q

Steps of DNA Replication

A

Enzyme DNA helicase opens one short segment of helix at a time // exposing its nitrogen bases

Replication fork – the point where the DNA is opened up (like two separated halves of a
zipper)

DNA polymerase molecules move along each strand in opposite directions /// read the exposed bases /// matches complementary free nucleotides

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27
Q

the polymerase molecule moving toward the replication fork makes a _____

A

long, continuous, new strand of DNA

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28
Q

the polymerase molecule moving away from the replication fork makes ______

A

short segments of DNA at a time …DNA ligase joins them together

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29
Q

semiconservative replication

A

each daughter DNA consists of one new helix synthesized from free nucleotides and one old helix conserved from the parental DNA

30
Q

new histones are synthesized in ____

A

cytoplasm

31
Q

each DNA polymerase works at a rate of _______ per second

A

100 base pairs

32
Q

thousands of ____ molecules work simultaneously on each ___ molecule

A

polymerase ; DNA

33
Q

all 46 chromosomes are replicated in ___ hours

A

6 - 8

34
Q

DNA polymerase may make mistakes and will

A

replace the the misplaced nucleotide. 1 in 1 billion errors happen

35
Q

Mutations

A

changes in DNA structure due to replication errors or
environmental factors (radiation, viruses, chemicals)

36
Q

Cell Cycle

A

a cell’s life cycle that extends through several phases to
produce two identical cells

37
Q

Interphase

A

occurs when the cell is doing what it is programed to do.

it is during interphase that the cell also doubles its DNA

38
Q

mitotic phase (M phase)

A

occurs when the cell
is ready to form an identical copy of
itself.

39
Q

A typical human cell might take about __ hours to divide

A

24

40
Q

What are the steps of interphase?

A

G1 phase, S phase, G2 phase. There is also an optional fourth
phase called G0 (G zero)

41
Q

G1 phase,

A

First gap phase
Growth and normal
metabolic roles

42
Q

S phase

A

S phase is when a copy of the
original DNA is made

43
Q

G2 phase

A

Second gap phase
Growth and preparation
for mitosis

44
Q

G0 (G zero) phase

A

Cells that leave the cell cycle
to “rest” / temporary pause

45
Q

How many chromosomes are in each new daughter cell after mitotic phase?

A

46

46
Q

Functions of mitosis

A

– development of the individual from one
fertilized egg to some 50 trillion cells
– growth of all tissues and organs after birth
– replacement of cells that die
– repair of damaged tissues

47
Q

Four phases of mitotic phase

A

– Prophase
– Metaphase
– Anaphase
– Telophase

48
Q

DNA is a polymer of ______ . The polymer can exist
in different forms – either as diffused _____ or condensed
_____

A

nucleic acids ; chromatin ; chromosomes

49
Q

DNA during S phase appears as _____

A

chromatin

50
Q

during prophase, chromatin shortens and thickens then coiling into compact rods called ______. Makes it easier to distribute
to daughter cells than when in form of _____

A

chromosomes ; chromatin

51
Q

At end of S phase /// individual chromosomes are copied but
held together /// each pair are now called ______ _____

A

sister chromatids

52
Q

At end of S phase, how many chromosomes are in the the parent cell?

A

92

53
Q

Mitosis: Prophase

A

Chromosomes condense
and nuclear envelope
breaks down. Spindle
fibers grow from centrioles.
Centrioles migrate to
opposite poles of cell

54
Q

Mitosis: Metaphase

A

Now chromosomes are aligned on cell equator

55
Q

Cell equator

A

swaying slightly and awaiting signal that
stimulates each of them to split

56
Q

Mitotic spindle

A

lemon-shaped array of spindle
fibers
– long spindle fibers (microtubules) attach to
chromosomes at kinetochore
– shorter microtubules (aster fibers) anchor
centrioles to plasma membrane at each end
of cell

57
Q

Kinetochore

A

point where chromatids attach to each
other

58
Q

Mitosis: Anaphase

A

separates the two chromatids at centromere
(point of chromatid attachment)

59
Q

During anaphase, ________ in kinetochore crawl along the spindle fiber as the fiber itself is ______ and disassembled at the chromosomal end

A

motor proteins ; ‘chewed up’

60
Q

Each daughter cell following mitosis are genetically ____

A

identical

61
Q

Mitosis: Telophase

A

chromatids (the daughter chromosome) cluster on
each side of the cell

62
Q

During telephase, rough ER produces new _____ around each cluster and each nucleus forms ____

A

nuclear envelope ; nucleoli

63
Q

Cytokinesis

A

the division of cytoplasm into two cells

cell eventually pinches in two

telophase is the end of mitosis but overlaps with
cytokinesis

64
Q

Cytokinesis creates the ______ around the equator of cell

A

cleavage furrow

65
Q

When may cells divide by mitosis?

A
  • If they have enough cytoplasm for two daughter cells
  • If they have doubled their DNA (made complete copy of all chromosomes).
  • If they have adequate supply of nutrients
  • If they are stimulated by growth factor – chemical signals secreted by blood platelets, kidney cells, and other sources
  • If neighboring cells die. This opens up space in the tissue for new cells and prevents contact inhibition.
66
Q

What will inhibit mitosis?

A
  • When nutrients or growth factors are withdrawn
  • If existing cells are too closely packed with neighboring cells / no room for new cells
  • Contact inhibition
67
Q

Contact inhibition

A

the cessation of cell division in response to contact with other cells

68
Q

father of Classical Genetics.

A

Gregor Mendel

coined the terms dominant and recessive traits

69
Q

Charles Darwin wrote ________. He explained how
_____ and _______ create new species.

A

On the Origin of Species ; Evolution ; Natural Selection

70
Q

Darwin and Mendel work is known as _______

A

Classical Genetics

71
Q

Our understanding of genetics was updated and renamed ____ in the 1940’s to incorporate the role of DNA .

A

Modern Genetics

72
Q

epigenetic trait

A

stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence

A&P : Unit 1 (11 decks)

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