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Biology > Topic Three - Cell Cycle, Mitosis and Stem Cells > Flashcards

Topic Three - Cell Cycle, Mitosis and Stem Cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Cell Division

A

All cells are derived from pre-existing cells (Cell Theory)

Cell division is the process by which cells produce new cells

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2
Q

Cells grow in number, not it size

A

Smaller cells more efficient (cellular transport,
cellular communication/signaling)

Easier to take in nutrients & get rid of wastes

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3
Q

How often do cells divide

A

Short Lifespan = Intestines, white blood cells, skin cells
Do not divide after birth = Muscle , nerve cells, brain cells, gametes

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4
Q

Chromosomes

A
  • plans for making cells are in DNA
  • tightly coiled dna
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5
Q

Why do cells need to divide

A

Growth, repair, reproduction

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6
Q

Growth

A

not increasing in size but in number

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7
Q

Cells divide at

A

different rates

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8
Q

Binary Fission

A

Is cell division in Prokaryotes

  • asexual reproduction
  • DNA replication, chromosome segregation and cytokinesis
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9
Q

Chromatin

A

Long thread-like DNA in a non diving cell

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10
Q

Chromatin to chromosome

A

Duplicates itself and then coils up into chromosomes
more efficient division

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11
Q

Chromatid

A

2 identical sisters that are attached in the middle called a centromere
when a cell divides, the sister chromatids separate and 1 goes to each new cell
so each cell ghet a full set of chromosomes.

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12
Q

Haploid

A

One set of chromosomes
Gametes (sperm and ova)

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13
Q

Diploid

A

Two sets of chromosomes
all other body cells other than gametes

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14
Q

Somatic cells

A

Body cells

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15
Q

Somatic cells have the same kind and number of

A

chromosomes

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16
Q

Cells spend most of their time in

A

Interphase

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17
Q

The nucleus divides at

A

Mitosis

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18
Q

The Cytoplasm divides at

A

cytokinesis

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19
Q

The cycle is about _____ hours for most animal cells

A

12-24

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20
Q

G1

A

Cellular contents, excluding chromosomes, are duplicated, cell is growing, making more cytoplasm and organelles, preparing to replicate DNA

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21
Q

S

A

Each of the 46 chromosomes are duplicated by the cell, DNA is in the form of chromatin (uncoiled DNA) and it is not visible

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22
Q

G2

A

The cell double checks the duplicated chromosmes for error and make any repairs, cell prepares for nuclear division

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23
Q

Mitosis only occurs is the cell is

A

large enough and the dna is undamaged

24
Q

G0

A

Occurs in cells that are not replicating and stay in growth phase 1
- nerve cells (brain damage is irreversible)

25
Q

terminally differentiated

A

cells that have lost the ability to replicate

26
Q

What are the 4 stages of Mitosis

A

Prophase, metaphase, anaphase, telophase

27
Q

interphase

A

The longest part of the cell’s life cycle, the resting stage (cell isn’t dividing)

  • DNA replication occurs
  • period of growth and development
  • cell grows, carriers out normal cell activities, replicates all other organelles
  • By the end of interphase the cell has two full sets of chromosomes and is large enough to begin the division process
28
Q

Prophase

A

1
Chromosomes condense and are more visible.

The nuclear membrane (envelope) disappears.

Centrioles have separated and taken positions on the
opposite poles of the cell.

Spindle fibers form and radiate toward the center of the
cell.

29
Q

CHROMOSOMES CONDENSE AT THE START OF
MITOSIS.

A

DNA WRAPS AROUND PROTEINS (HISTONES) THAT
CONDENSE IT.

30
Q

Metaphase—(Middle)

A

2
Chromosomes line up across the middle of the
cell.

Spindle fibers connect the centromere of each
sister chromatid to the poles of the cell.

31
Q

Anaphase—(Apart)

A

3
Centromeres that join the sister chromatids split.

Sister chromatids separate becoming individual
chromosomes.

Separated chromatids move to opposite poles of
the cell.

32
Q

Telophase—(Two)

A

4
Chromosomes (each consisting of a single
chromatid) uncoil.

A nuclear envelope forms around the
chromosomes at each pole of the cell.

Spindle fibers break down and dissolve.

Cytokinesis begins.

33
Q

Cytokinesis

A

the division of the rest of the cell (cytoplasm and
organelles) after the nucleus divides.

Animal cells
- In animal cells the cytoplasm pinches in forming a cleavage furrow:

Plant Cells
- In plant cells, a cell plate forms creating a cell wall

34
Q

Cell Cycle checkpoints

A

g1 - cell size, nutrients, growth factors, DNA damage

g2 - cell size, DNA replication

mitosis - chromosome attachment to spindle

35
Q

Apoptosis (programmed cell death) - humans

A

SKIN CELLS CALLED KERATINOCYTES SELF
DESTRUCT IN AN ORDERLY AND PROGRAMMED
MANNER CALLED APOPTOSIS

THIS OCCURS EVERY 3 WEEKS, CAUSING YOU TO
SHED LAYERS OF SKIN VERY OFTEN

A HUMAN EMBRYO LOSES THE WEBBING
IN BETWEEN ITS FINGERS AND TOES THROUGH
THIS PROCESS

36
Q

Apoptosis

A

VERY IMPORTANT DURING DEVELOPMENT, SHAPING ORGANS AND TISSUES, TO REMOVE OLD CELLS OR IF A CELL HAS BECOME INFECTED
CONTROLLED BY MANY GENES THAT PRODUCE ENZYMES THAT SHRED DNA INTO THOUSANDS OF FRAGMENTS
THE MEMBRANE FORMS BLEBS MADE OF PLASMA MEMBRANE
MACROPHAGES (WHITE BLOOD CELLS) ENGULF THESE AND RECYCLE THEM

IT NORMALLY HAPPENS IN CELLS THAT HAVE BEEN AROUND IN THE BODY LONG ENOUGH THAT THEY’RE WORN OUT AND SO THEY NEED TO BE REPLACED BY NICE, NEW YOUNG CELLS

WHEN THAT DOESN’T HAPPEN, IT CAN CAUSE CANCER

SO APOPTOSIS CAN BE NORMAL, AND IN THE ABSENCE OF APOPTOSIS, THAT CAN LEAD TO CANCER

TOO MUCH APOPTOSIS IN AN OTHERWISE NORMAL HUMAN BEING WILL RESULT IN A NUMBER OF SO-CALLED NEURODEGENERATIVE DISEASES WHERE CELLS DIE WHEN THEY’RE NOT SUPPOSED TO DIE

37
Q

Cell division control

A

DNA controls all cell activities including cell division

Some cells lose their ability to control
their rate of cell division – the DNA of
these cells have become damaged or
changed (mutated)

If the cell’s apoptosis genes have been
mutated then cell death will not occur

These super-dividing cells form masses
called tumours

38
Q

Cancer

A

cell division must be controlled, otherwise, cell growth will occur without limit (cancer)

39
Q

PROTO-ONCOGENES

A

(GENES THAT PROMOTE CANCER)
IF MUTATED THEY CAN PRODUCE ONCOGENES → CANCER

ANY CHANGE IN THESE GENES THAT ENHANCES THEIR
FUNCTION CAN PROMOTE UNCONTROLLED CELL GROWTH
AND CANCER.

40
Q

GENETIC CONTROL OF THE CELL CYCLE

A

TWO MAIN TYPES OF GENES THAT REGULATE THE CELL CYCLE

THEY HAVE BEEN STUDIED BECAUSE THEIR FUNCTIONS ARE
LINKED TO CANCER

proto-oncogenes
tumour suppressor genes

41
Q

TUMOUR SUPPRESSOR GENES (INHIBIT CELL DIVISION)

A

THEY NORMALLY KEEP THE CELL FROM DIVIDING TOO
QUICKLY, LIKE BRAKES SLOWING A CAR DOWN. MOST OF
THESE ARE MUTATED/SILENCED IN CANCER.

42
Q

3 types of mutagens

A

CHEMICAL MUTAGENS

PHYSICAL MUTAGENS

BIOLOGICAL MUTAGENS

43
Q

Chemical Mutagens

A

THEY INTERFERE WITH DNA BY INTERRUPTING ITS
STRUCTURE, SEQUENCE OR REPLICATION. IF THE MUTATION
AFFECTS CELL CYCLE REGULATION GENES, THIS INHIBITS
CHECKPOINTS AND CAUSES UNCONTROLLED CELL DIVISION.

44
Q

PHYSICAL MUTAGENS

A

PHYSICAL FACTORS INCLUDE ULTRAVIOLET LIGHT, X-RAYS AND
NUCLEAR RADIATION CAN CAUSE MUTATIONS IN DNA. UV LIGHT
IS ABSORBED AND DAMAGES DNA IN SKIN CELLS. OVEREXPOSURE
TO THE SUN MAKES IT HARD FOR REPAIR MECHANISMS TO KEEP
UP.

45
Q

Biological mutagens

A

VIRUSES CAN CAUSE MUTATIONS OR IMPAIR
CELL CYCLE REGULATION. SOME HAVE
ONCOGENES THAT STIMULATE CELL
DIVISION. SOME CAN INSERT THEIR DNA INTO
HUMAN CELL CYCLE REGULATION GENES,
CAUSING THEM TO LOSE CONTROL OF CELL
DIVISION, LEADING TO CANCER.
EG. HUMAN PAPILLOMAVIRUS.

46
Q

Proto-oncogenes speed up the…

A

cell cycle

47
Q

IF THERE IS A MUTATION IN A PROTO-ONCOGENE…

A

THEN IT
CREATES AN ‘ONCOGENE’ THAT SENDS MESSAGES TO THE CELL
TELLING IT TO DIVIDE REPEATEDLY

48
Q

IF THERE IS A MUTATION IN A TUMOR SUPPRESSOR GENe…

A

THEN
THE NORMAL MESSAGES TELLING THE CELL TO SLOW DOWN
DIVISION ARE STOPPED, CAUSING DIVISION TO HAPPEN FASTER

49
Q

Specialised cells

A

cells become specialised through a process called differentiation
once they have committed to a path way there is no turning back

50
Q

Stem cells

A

undifferentiated cells that have the potential to replicate and differentiate into various tissues,

51
Q

Potency

A

describes how many types of specialized cells a stem cell can differentiate into, they can be totipotent, pluripotent and multipotent

52
Q

Totipotent stem cells

A

are found in the first few divisions of
a zygote

can differentiate into ALL cell types

53
Q

Pluripotent stem cells:

A

are found in the inner cell mass of a
blastocyst (128 cell embryo)

can differentiate into any cells in the
body except the placenta

54
Q

Multipotent stem cells:

A

are found in bone marrow or
umbilical cords

can differentiate into a limited
number of cells related to their tissue
of origin

55
Q

Types of stem cells

A

1 - Embryonic stem cells (ESC)
- taken from a 5-day-old embryo (blastocyst)
- they keep their potency after multiple cell divisions
- pluripotent
- created to be destroyed

2- Adult stem cells (ASC)
- undifferentiated cells found in tissues )brain, bone marrow, liver, fat)
- multipotent
- used to treat bone disorders and leukemia
- come from patients’ own body so they won’t reject them

56
Q

induced pluripotent stem cells

A

Differentiated cells can be treated and turned back into pluripotent
stem cells

57
Q

Stem cell therapy and research

A

they can replace damaged cells in the body and treat diseases
scientists can clone them, differentiate them and then give them to a patient
- ASC - a blood disease
- ESC - Damaged nerve cells

there are high risks, rejecting them from someone else, virus contamination, ethical problems ESC

Biology (13 decks)

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