Asexual Reproduction Flashcards
During which part of the cell cycle is DNA replicated?
interphase
What is different between how plant and animal cells use the cell cycle?
Plant cells create a cell plate since they are very rigid.
What is the purpose the the cell cycle checkpoints?
To repair damaged cells before they enter cell division.
This is the cell cycle checkpoint that makes sure DNA has been replicated correctly during S phase.
G2 Checkpoint
Name the 3 checkpoints of the cell cycle
G1 checkpoint, G2 checkpoint, and mitosis/metaphase checkpoint
Why do cells replicate ( simple term )
Cause cells come from preexisting cells
What is cell replication?
Process of cell division, a parent cell divides, forming two genetically identical daughter cells
also in asexual reproduction
Why is cell division important ( 3 )
- Allow organisms to grow
- Means damaged tissues can be repaired
- Involves the creation of new gametes, which can eventually lead to offspring
- If it’s too big, it cannot get enough nutrients into the cell and wastes out of the cell
Cell division equation
C=2 ^n
Where do cells spend most time in ?
Interphase
Interphase factors
- Often temporary
- Cells continues to carry out regular cellular functions without increasing in size or altering structure.
Do all cells over go replication
- Highly specialised cells do not undergo cell replication, so remain permanently in G0 Phase
etc. neurons, red blood cells
What happens in G1 phase?
Check to see if DNA is damaged
- growing enough ?
- Gains energy
- cell has resource it needs
- Undergoes metabolic processes and cellular growth in preparation for division
-Duplication of content
eg, proteins for DNA synthesis
What happens in S phase?
Chromosomes replicate in the nucleus
centrioles/Centrosomes duplicates
-synthesis of chromosomes or dupilcation of chromosomes
What happens in G2 phase?
Check to see if DNA is replicated properly.
POST-DNA SYNTHESIS
growing well enough?
Gains energy
double checking duplication of chromosomes for errors and if needed repairs
Undergo metabolic processes and cellular growth in preparation for division
CHROMOSOME
two heads: sister chromatids
the middle dot: centromere
thread-like structure formed from DNA and proteins
During the G0 resting phrase, cell wills..
carry out regular cellular functions
Where does mitosis occur?
In body cells, any cell in the body that isn’t a sperm or egg
What does mitosis involve the creation of?
two genetically identical daughter cells from a single parent cell
4 stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What is cytokinsis?
Division of the cytoplasm that results in two daughter cells.
Why do cells division?
Growth Reproduction ( in single celled organism )
Repair
What happens in M checkpint phase? (3)
Spindle assembly checkpoint
Check for alignment of chromosomes
Apoptosis: programmed cell death, if any check fails
Mitosis in simple terms?
The division of the nucleus
results in identical complete copies of chromosomes packaged into two new nuclei.
Stages of cell cycle
Interphase Prophase Metaphase Anaphase Telophase
Whats in the interphase?
RESTING
Nucleus
Centrioles
Nucleolus
Nuclear envelope
Whats in the prophase?
Chromosome visible (consisting of two sister chromatids)
Developing spindle
as Centrioles move
pro-metaphase:
Nuclear envelope
Kinetochore microtubules
Whats in the metaphase?
Chromosomes line up on the spindle equator / equatorial plate
Centrosomes at one spindle pole
Whats in the anaphase?
Chromosomes pull apart,
sister chromatids seperate
but spindle on the sides
becomes shorter
one daughter chromosome/chromatids on each side
Whats in the telophase?
Nuclear membrane form on each sides , cytokinesis begins
cytokinesis in plant cells?
It begins when a new cell wall forms between the two cells.
cytokinesis in animal cells?
two new cells pinch and pull apart.
Whats in the G2 of interphase?
Centrosomes ( with centriole pairs) Chromatin (duplication) Nucleolus Nuclear envelop Plasma membrane
What are daughter cells called?
Diploid
HeLa cells?
A cell type in an immortal cell lined used in scientific research.
Oldest and common used human cell line
In humans, each cell (except sex cells) has how many chromosomes?
In humans, cells other than human sex cells, are diploid and have 23 pairs of chromosomes.
total 46
After mitosis, how many daughter cells are produced?
Two
After mitosis (in a human cell), each daughter cell has how many chromosomes?
After mitosis, each of the 2 daughter cells will also have 46 chromosomes.
How many phases are in MITOSIS?
4
Which phase of the cell cycle is the longest?
Interphase
During which phase does cytokinesis begin?
Telophase
4 splits in cell cycles
G1: growth
S: DNA synthesis/replication
G2: Growth and preparation for mitosis
M: Mitosis (cell division )
How do many organisms, especially unicellular organisms reproduce by mean of cell division?
Asexual reproduction
eg bacteria
What is chromatin?
Long and thread like DNA in a non-dividing cell
What is chromosomes?
Double, coiled, short DNA in a dividing cell
What does chromosomes have?
- Chromatid
- Centromere
What is centromere?
THE MIDDLE
the two identical sister chromatids attached at an area in the middle
What happens to chromatids when cell divides?
When cell divides, sister chromatids seperate and 1 goes to each new cell
chromosomes structure??
One vertical hoop is chromatid “ unduplicated”
Two vertical hoop is chromatid “ duplicated”
has centromere in the middle
What is a chromosomes made up of?
Two chromatids
one from mother and one from father
dna and proteins
what HAPPENS in interphase?
chromosome duplicate and become two identical chromatin, joined at the centromere
so from 46 to 92
what HAPPENS in prophase?
in the nucleus, the chromosomes condense.
in cytoplasm, spindle fibres form
centrioles form two from replication of one from interphase )
what HAPPENS in metaphase?
nuclear membrane breaks off, the spindle fibre attach to the chromosomes from one pole to another ,
chromosomes line up at the equator of the cell
what HAPPENS in anaphase?
spindle fibres shorten
centromere divides
so each chromosomes become, two seperate chromatin
what HAPPENS in telophase?
nuclear membrane moves from each set of chromosomes
chromosomes spring back out in a new nucleus
spindle fibres break down
what HAPPENS in cytokinesis?
cell membrane pinches in the two seperate sets of chromatins , and two identical daughter cells
same number of chromosomes as parent ( 46 each )
what is mitosis involved in
- growth
- cell repair
- asexual reproduction
what does the word chromatid described as?
newly copied chromosome, the identical copies
What is it called when cell has a typo?
Mutation with rogue cell
cancer treatment
slow-growing / one place? surgery
fast growing/ invading nearby tissues: radiation or even after surgery
spread: chemotherapy
frequently cell divides
likely drug to kill it (chemotheraputic drugs)
cancer treatment
how does cell grow..
by dividing
does cells divide in interphase
NOOOO
WHY ARE checkpoints useful?
If cell has an error, mutation, checkpoints is useful to prevent that cell from dividing more
check that the cell has no DNA damage,
sufficient resources throughout the cycle
healthy to continue to do it’s important processes such as DNA replication.
checkpoint in metaphase
make sure chromosomes, which are made of DNA are lined up in the middle correctly
attach to spindle correctly
what is apoptosis
cell self destructs
ensures that irreparable cells will not divide
what is G0
An exit in the cell cycle
receives a signal to differentiate
resources are insufficient to grow and divide.
some cells don’t go through the phases
resting phase
perform cell functions - but aren’t prepared to divide
time period cells spend in G0
- some temporarily ( eg. not enough resources around )
- neurons stay permenantly - never go to M phase - wont divide
Why does cell division remain important to an adult organism even after it is fully developed?
Even after growth, division remains important in normal cell turnover, such as in our skin and gut, where cells are continuously renewed.
Cells divide, differentiate, or die. What is differentiation?
Cells stop dividing to specialise in structure and function,
Once differentiated, some cells may divide again under certain conditions.
What are cell cycle regulators?
To remain healthy,
essential for an organism to maintain the right number of cells.
This is achieved primarily by regulating the ‘cell cycle.’
These cell cycle regulators are molecular signals that may stimulate or stop cell division, instruct cells to differentiate, or even initiate cell death.
proteins that control the progression of a cell through the cell cycle
THERE are Genes that encode these proteins.
Mutations in these genes can lead to cancer,
What happens if cell cycle regulators don’t function properly?
organisms may end up with too few or too many cells, this can cause problems.
harmless hair loss or the growth of warts to the development of life-threatening tumours.
G1 in details:
The cell increases in size and prepares to replicate its DNA.
end of this phrase the cell has to be sufficiently healthy to replicate its DNA.
If it’s undamaged and has enough resources then it keeps growing and divides, going into other phrases.
If not, the cell dies, or enters a resting state, also known as G0 phase.
S in details:
The synthesis phase, where a cell replicates its DNA.
end of this phase the cell has two complete set of chromosomes.
DNA is continuously monitored for replication errors, and if there is none it moves to G2 where the cell matures.
G2 in details:
Second gap phase.
The cell continues to grow and prepare for division.
DNA has no damage, all chromosomes have to be fully replicated and contain no other types of damage, and enough cell components.
Which factors determine whether a cell enters G0?
- Resources are insufficient to grow or divide.
- Organism’s stage in development.
Can cells leave G0?
Many neurons and muscle cells, remain in G0 and never re enter the cycle,
some tissues such as the liver, injury can cause cells to leave G0 and progress through the cell cycle and divide.
Stimulating proteins are encoded by (CELL REGULATORS)
proto-oncogenes. dominant ( one alles )
Inhibitory proteins are encoded by
suppressor genes. reccesive ( two alles )
two reasons why cells can form tumors.
Too much cell division
Too little cell death
cell cycle cause ( simple 3)
repair
growth
reproduction
at the end of replication in (copying DNA) interphase
there will be two identical sets of chromosomes
what happens in an animal cell, that does not happen in a plant cell?
centrioles are duplicated
What is the substance in cytokinesis?
Each new cells now have an identical set of chromosomes, with half the organelles from each parent cell
difference between animal cell and plant cell in cytokinesis
animal cell: squeeze around the middle, allowing cytoplasm to divide in two parts.
plant cell: cell wall is rigid,
cell plate forms in the middle
cell membrane will form between the two cells
cell wall form where cell membrane
what type of cells divide by binary fission?
prokaryotes such as bacteria cells
binary fission steps?
- replication of circular dna molecule
- attach of the two newly formed dna molecules to diff parts of plasma membrane
- lengthening cell
- plasma membrane constricts in the middle
two dna molecules
new cell walls formed - cell division in short time
cytokinesis animal cell?
ring of protein molecules form a cleavage furrow
cytokinesis plant cell?
cell plate form and grows towards cell wall
when does asexual reproduction occur?
one parental organism gives rise to two identical offspring.
types of asexual reproduction
4
fission ( bacteria )
budding (hydra)
vegetative reproduction ( strawberry)
parthenogenesis ( aphids )
advantages of asexual reproduction
- parent can reproduce without mate
- genetically-identical offspring produced well suited to environment
-compare to sexual reproduction-
offspring produced faster RATE , SAVES energy
- high number - resilient
- everyone can reproduce (not just FEMALES)
DISadvantages of asexual reproduction
- little variation in population. environment change = population may not survive
- rapid population
- no genetic variation
- Evolution is slow
growth=lead to competition for resources
- mutation in parent DNA will be passed to offspring
mutual neg = die
what are clones
organisms with identical genetic makeup
how is clones produced?
asexual reproduction
how are plant clones produced
vegetative reproduction = tissue culture
how are animal clones produced
separating embryo cells
through somatic cell cloning
what clones is less problematic
plantssss
why does cloning of whole organism raise issues?
6
- cost of techniques
- efficiency of technique
- health effects
- rights of an embryo
- change to gene pool for species
what is asexual reproduction?
offspring from single parent organism
what types of process is mitosis?
asexual process
simple process binary fission
- parent cell
- dna duplication
- cytoplasm division
- two daughter cell
simple process budding
hydra, yeast
- parent hydra
- developing bud
- new bud
- new hydra
simple process spores
- spores
2. food source
simple process
parthenogenesis
a form of reproduction in which an egg can develop into an embryo without being fertilized by a sperm
fragmentation
starfish, planaria
- adult hydra
- amputation
- regenration of tiny hydras
- growth
vegetative propagation
- cutting
- runners
- tubers
vegetative propagation: cutting
from root cutting, include strawberry, raspberry, lilac etc
shoot of plant contains stem cells - able to differentiate to form stems and tissues
vegetative propagation: runners
stem portion of plant that trends to grow horizontally
stolon plants (strawberries, ginger )
vegetative propagation:
tubers
potatoes, fleshy underground storage structures composed of enlarged part of the stem.
on the plant
in potato and yams and in roots that have been modified to store nutrients.
TWO MAIN methods of cloning used in science
method 1: embryo transfer
method 2: somatic cell nuclear transfer
what is embryo transfer?
Sperm taken from bull
cow is artificially inseminated with sperm
embryos stem cell develop and removed from uterus
embryos split into several smaller cells.
-become specialised, each can grow into a new cell
identical embryos are transplanted into host mother
cows will be clown of each other but NOT cow mothers due to bulls sperm
(not surgrotes )
what is embryo?
unborn offspring in the process of development
embryonic division
early embryo –> cell seperate —> identical embryos —-> implanted in surrogates —-> identical offspring (clones )
somatic cell nuclear transfer?
- dolly the sheep
body cell taken from sheep A (-)
egg cell taken from sheep B (+)
nucleus removed (-) from somatic cell
empty egg cell (+)
DNA from sheep A inserted in egg cell from sheep B
embryo cells have same gentic info adult as body cell
Fused cell develops into embryo which is placed in uterus of host/surrogate mother
lamb is clone of sheep A - body cell (BODY CELL TAKEN )
CULTURES ADULT skin cell example
UV destroy nucleus of unfertilised egg
removal nucleus from adult skin cell
transfer of nucleus into enucleated egg
cloned organism develop
difference between natural twinning and artificial twinning?
Artificial embryo twinning is a relatively low-tech
Natural twinning occurs in the first days after egg sperm joins, each half ends up dividing on its own and becoming genetically identical
YES OR NO
Sperm taken from a mole goat is combined with a female’s egg in a petri dish. The resulting embryo is implanted into the female’s uterus to develop
NO
A sheep embryo, composed of 16 cells, is removed from the mother’s uterus and separated into individual cells. Each cell is allowed to multiply, creating 16 separate embryos, which are then implanted in different female sheep to develop to maturity.
YES
A cow with many desirable traits is stimulated with hormones to produce a number of egg cells. Each of these eggs is fertilized and implanted into a surrogate mother.
NO
In vitro fertilization.
NO
Cell nuclei from an extinct woolly mammoth are placed into enucleated cow cells.
YES
Four reasons for pros of cloning
Cloning in medicine
Reviving endangered or extinct species
Reproducing a deceased pet
Cloning livestock
clone a dinosaur?
- well-perserved DNA
- Closely related species
Why would a farmer want to clone livestock?
Animals such as cattle and pigs are efficient producers of high-quality milk or meat.
- What are two reasons a person might want to clone a human?
Possible solution to infertility problems.
Cloning of geniuses, who work could advance society.
- Why would Frankie #2 be different from Frankie #1?
nature vs nurture
- different mitochondria
- mitochondria has own chromosome, made of DNA, and divide into genres
- mitochondria comes from mother, when cloned is made the egg cell used to received the donor nucleus is already filled with mitochondria contributed by the egg donor
Why does cloning have such a high failure rate?
embryo develops, cells begin to differentiate into muscle, nerve, liver, and other types. Part of the differentiation process involves adding and removing chemical tags on the DNA, which keeps genes turned “on” that are necessary for the function of that cell type and keeps others turned “off.”
what do we count chromosomes by
by chromere in the middle
half bodies (46 chromosomes = 46 chromatids 0
full bodies
46 chromosomes - 92 chromatids
its 46 chromosomes cause of no. of chromere
good way to identify interphase to prophase
the chromosomes over lap with chromere
what gap is G2?
Its the second gap
what does centrioles do between prophase and metaphase
move away from one another towards opposite ends of cell due to lengthening of microtubules that forms between them
- Why is the whitefish used to study mitosis?
e whitefish embryos have cells that are rapidly dividing, making it easier to see the different stages of mitosis under a microscope as the fish embryo is growing. This is why mitosis is only visible in cells that are dividing.
- What are the four stages of mitosis?
Prophase, Metaphase, Anaphase & Telophase.
How long does it take for mitosis to complete?
Mitosis takes several hours ( up to 24 hours full cycle. )
what is kinetochores
this is after prophase where microtubules also lengthen by addition of tubulin proteins to the growing end
centrosomes/centroles function
help separate DNA during M phase.
How long does the cell cycle take?
A typical human cell might take about 24 hours to divide
90%
does sex and fertilisation required for Asexual reproduction?
NOOOOO
HOW MANY CENTRIOLES IN A CENTROSOMERS
THERE ARE TWO CENTRiOLES IN A CENTROSOMES
2 EACH SIDE
the nuclear envolope around centrosome?
NOO
WHERE IS REGULATE
BETWEEN G1 AND S
BETWEEN G2 AND MITOSIS
CONTROL of cell cycle
p53, proteins block progession of cell cycle
tuber supperor genes = mutuatuion = loss of control = cancer
tuber supperor genes
very important
avoid cancer
helps to divide when nesscarry
normal cell vs cancer cell
normal cell has apoptosis
cancer cell= continues dividng and has no tuber supperor genes
differences between mitosis and cytokinesis
Mitosis is the division of genetic material/DNA/chromosomes while cytokinesis is division of the
cytoplasm.
Mitosis results in two identical daughter nuclei enclosed in one cell, while cytokinesis results in two
daughter cells,
Mitosis precedes (comes immediately before) cytokinesis.
Cytokinesis occurs in eukaryotes and prokaryotes, whereas mitosis occurs only in eukaryotes
event occuring in metaphase
- Replicated chromosomes attach by centromeres to spindle fibres.
- Replicated chromosomes line up across the equator of the cell.
event occuring in prophase
- Chromosomes condense/appear as individual strands.
- Nuclear membrane breaks down.
- Centrioles move to opposite ends of the cell (in animal cells).
event occuring in anaphase
- Spindle fibres shorten/retract to opposite ends of the cell.
- Sister chromatids of replicated chromosomes separate at centromeres.
- Sister chromatids are pulled to opposite ends of the cell.
statement that cell N is at interphase
Chromosomes in cell N are indistinct/not observed as individual strands.
The nucleus in cell N appears as a clearly outlined circular object in centre of cell; a nuclear
membrane is present.
A nucleolus is visible inside the nucleus of cell N.
A significant difference between interphase and mitosis is that:
During interphase there is no arrangement/movement/division/separation of chromosomes, while in mitosis,
chromosomes are arranged/moved around (attached to spindle fibres).
At the end of mitosis two daughter nuclei are present in the cell, while interphase ends with one nucleus
present in the cell.
Interphase involves growth of the cell /synthesis of a new set of chromosomes, while during mitosis, there is no
cell growth/no replication of chromosomes.
blackberry plant grws root send up shoots meteres from plant.
new shoots form vetative reproduction called sucker
if seperated roots of main balckberry , sucker form to new plant
Plants produced by suckers are clones of the original blackberry plant.
The explanation for the difference in strawberry plants grown by runners compared to the offspring from the
seeds is that
Growth of runners is a form of vegetative reproduction/asexual reproduction.
Asexual reproduction produces offspring with the same genetic features as the parent, therefore, the
size and flavour of the fruit is the same as the parent.
Seeds are produced by sexual reproduction/not produced by asexual reproduction, so offspring are
genetically different from the parents, resulting in different fruit quality to that seen in parent plants.
Two arguments against cloning farm animals, such as cattle are (
It is very expensive.
It is not very successful/reliable.
health problems
What happens when the Cell Cycle goes wrong
Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms that regulate the cell cycle.
process of Binary Fission
An organism’s duplicates its genetic material and DNA and then divides into two parts ( cytokinesis ) with each new organism receiving one copy of DNA.
process of Budding
New organism develops from an outgrowth or bud due to cell division at one particular site. These buds develop into tiny individuals, and when fully mature, it detaches from the parent body and becomes independent.
process of Parthenogenesis
Natural form of asexual reproduction in which growth and development of embryos occur without fertilization by sperm.
In animals it’s development of embryos from an unfertilized egg cell. So female can reproduce without a male mate.
process of Spores
Typically one celled that
Is adapted for dispersion and
Surviving for extended periods of time
In unfavorable conditions.
process of Fragmentation
Parent organism breaks into fragments, each capable of growing independently into new organism.
process of Runners & Tubers
Runner are specialised aerial stems, a natural agent of increase and spread. Tubers are specialised storage stem of certain seed plants. They are usually short and thickened and typically grow below the soil.
difference between mitosis in plant and animal cells
The main difference between animal mitosis and plant mitosis is that the mitotic spindle in animal mitosis is formed with the help of two centrioles whereas mitotic spindle in plant mitosis is formed without any centrioles. Mitosis is followed by cytokinesis
in binary fission
a cicrcular dna molecules is replicated
why is interphase the most shown
chromosome are not visible, dna is not condensed, enable dna (genome) to be functional
so genes are accessible for the cell to normally function to produce proteins need for metabolism , dna replication
what is scnt
nucleus is removed from a somatic cell and placed into en enucleated ovum
asexual reproduction known as cloning
how can cloned egg be produced by mother (animal can be asexual )
mitosis
adv of sexual - mass
populatoin
good season, temp food they eat and grow
what are somatic cells
not sex cells
zygote is one , and normal body cells
if father is affect with non-disjuncition ( klinefelter ) explain effect of child
see pic
polygentic and skin colour
see pic
