Cell Division, Diversity And Organisation Flashcards
Mitosis is the type of nuclear division that produces _________ __________________ daughter cells
Genetically identical
Meiosis is the type of cell division that produces ___________ ________________ daughter cells
Genetically different
____________ is used to produce gametes in humans
Meiosis
___________ produces new tissue in the human body
Mitosis
All cells produced by mitosis will have the _______ number of chromosomes as the parent cell
Same
All cells produced by meiosis will have ___________ the number of chromosomes as the parent cell
Half
Define somatic cell
Anything that isn’t a gamete
What is a haploid
A cell with half the number of chromosomes
What is a diploid
A cell with paired chromosomes
Name three uses of mitosis
Growth of tissues
Replacement of cells (repair tissue)
Proliferation of white blood cells
What does proliferation mean
Reproduce
How many chromosomes in a:
Haploid
Zygote
Somatic cell
23
46
46
Define homologous chromosomes
A pair of chromosomes: one paternal and one maternal
What is a centromere
A point that holds the two chromosomes together
Why is it that we can see chromosomes through a microscope
Because the chromosome has replicated and have become supercoiled (coiled around a histone protein)
What. Happens in the first growth phase of the cell cycle
Protein synthesis
Organelles replicate
Growth of cells
What happens during the synthesis phase of the cell cycle
DNA replication
What happens during the second growth phase of the cell cycle
Cell continues to grow in size
ATP is made and duplicated
DNA is checked for errors
What happens during the mitotic phase of the cell cycle
Prophase
Metaphase
Anaphase
Telophase
What is G0
The name given to the phase when the cell leaves the cell cycle ( either temporarily or permanently)
For what reason could a cell go into G0
- There is a mutation in the DNA
- DNA has been damaged
- Once the cell has differentiated (the cell is specialised to carry out a specific function so is no longer able to divide- it will permanently leave the cell cycle)
Are somatic cells:
A) haploid cells
B) diploid cells
Diploid
What type of reproduction is mitosis used in
Asexual
What must the cell have in order to divide
What is involved to ensure this
Be the right size
Replicated DNA is error free
The chromosomes are in correct positions
Checkpoints
What do checkpoints in the cell cycle do
They monitor and verify whether processes at each phase of the cell cycle has been accurately completed
G1 checkpoint:
- What does it check for?
- Where is it?
Cell size
Nutrients
Growth factors
DNA damage
At the end of G1 phase before S phase
S phase checkpoint
- What does it check for?
- Where is it?
DNA replicated correctly
DNA damage
At the end of S phase
What is another name for G0
Resting phase
G2 checkpoint
- What does it check for?
- Where is it?
Cell size
DNA replicated correctly
DNA damage
At the end of G2 phase before the mitotic phase
Spindle assembly/ metaphase checkpoint
- What does it check for?
- Where is it?
Chromosomes attached to spindle
Metaphase of mitosis
What part of the plant must you use to observe mitosis
A growing part of the plant, e.g root or shoot
Why is it that root tip should be used when observing mitosis
Here there is meristematic tissue so is where cell division takes place
What type of slide would be prepared for observing mitosis
What type of stain would be used
Squash slide
Acetic orcein/ methylene blue
Describe what happens during prophase
Chromosomes supercoil and become visible-consist of two chromatids held together by a centromere
Centrioles divide- move to opposite poles
Spindle fibres come out from centrioles
Nucleolus disappears and nuclear envelope disintergrates ( AT THE END OF PROPHASE)
What happens during metaphase
Chromosomes align at the EQUATOR of the cell helped by spindle fibres
Chromosomes are not paired but are still attached to spindle fibres by their centromere
Describe what happens during Anaphase
Spindle fibres pull the chromatids apart > now chromosomes
Centromere divides
Chromosomes move to opposite poles of the cells
Chromosomes number doubles
Describe what happens in telophase
A nuclear envelope forms around each group of chromosomes
The chromosomes uncoil returning to chromatin
Nucleolus is formed
When does cytokinesis occur in animal cells
Between telophase and interphase
What happens during cytokinesis
The cell surface membrane on each side joins up
Creating two separate cells
What do plant cells not have which is important in mitosis
Centrioles
Describe cytokinesis in plant cells
The vesicles fuse with each other (form cell plate) and the cell surface membrane dividing the cell into two
New sections of cell wall then form along the new sections of membranes
Name a difference in organelles between plant and animal cells
Plant cells don’t have centrioles
Animal cells do
How do yeast cells reproduce
Asexually
Budding
Describe the cells made in budding
Genetically identical
How does the nucleus divide in yeast cells
Mitosis
Describe the process of budding
1) swelling on the surface of the cell (dna is replicated)
2) mitosis occurs
3) the nucleus divides
4) nucleus cytoplasm and organelles move into the swelling
5) the swelling pinches off by budding to form 2 genetically identical cells
Name an example of a plant that produces asexually
Strawberry plants
Potatoes
How do bacteria reproduce
Asexually
Binary fission
What type of cell is a bacteria
Prokaryotic
Describe embryonic stem cells
Unspecialised/ undifferentiated cells that divide by mitosis, can differentiate into other cell types, once specialised they loose the ability to divide (go into G0)
What does pluripotent mean
Can form all types of tissue but not whole organisms
Define potency
Ability to differentiate into different cell types
Define Multipotent
stem cells that can only form a range of cells within a certain type of tissue
Where could u find pluripotent stem cells
Early embryos
What is cambium
A group of cambium cells form meristematic tissue
They can differentiate into xylem and phloem cells
Where can u find meristematic tissue
apex of Shoot and root tips
What dies apex mean
Tip
Describe embryonic stem cells
Cells present at very early stage of embryo development
They are totipotent
A blastocyst is a mass of these cells
Once in a blastocyst they are pluripotent
Describe tissue stem cells
Found in bone marrow (these can produce erythrocytes and neutrophils)
Are multipotent
Where can we find blood stem cells
Umbilical cord stem cells
Name 4 uses of stem cells
Type 1 diabetes- produce insulin
Heart disease- repair muscle tissue
Spinal injuries- repair spinal cells
Treatment of burns-stem cells to grow skin
Evaluate using stem cells (ethics)
✅improves quality of life for patient
✅embryos left over from fertility treatment are discarded anyway
🚨religious objections-murder
🚨lack of consensus over who has rights to the embryo
Give three reasons why the cell could no longer undergo mitosis
The cell has already differentiated and become specialised
The cell is in G0
The cells cytoskeleton cannot function
How are erythrocytes adapted to carry out there function
Biconcave shape gives large SA:Vol ratio
No nucleus- optimum oxygen uptake
Small so can fit through capillaries
How are neutrophils adapted to carry out there functions
Have a large multi lobed nucleus
Contain lots of lytic enzymes for hydrolysis of pathogens
Many ribosomes/rough ER to make enzymes
How are sperm cells adapted to carry out there function
Have acrosome which contains digestive enzymes that enable the sperm to penetrate the ovum
Flagellum allows movement
Lots of mitochondria (and ATP)
Describe the structure of epithelial Cells
Cells linked together with a membrane made of protein , they are ciliates to move substances in the trachea
Squamous to give a short diffusion path
Could have microvilli to increase SA
How is a palisade mesophyll cell adapted to carry out its function
Long and thin, has many moveable chloroplasts to capture the most light
Think cell wall increases rate of diffusion
Describe cytokinesis in plant cells
The vesicles fuse with each other (form cell plate) and the cell surface membrane dividing the cell into two
New sections of cell wall then form along the new sections of membranes
Name a difference in organelles between plant and animal cells
Plant cells don’t have centrioles
Animal cells do
Give three reasons why the cell could no longer undergo mitosis
The cell has already differentiated and become specialised
The cell is in G0
The cells cytoskeleton cannot function
Define tissue
E.g.
A group of cells that are specialised to work together for a particular function
Nervous
Epithelial
Muscle
Connective
Define organ
A group of different tissues working together for a common function
Define the term systems
A group of organs working together for a particular function
Describe the squamous epithelial tissue
One cell later thick
Large SA
Short diffusion pathway
Found in alveoli
Cheek lining
Endothelium of blood vessels
Describe the ciliates epithelial tissue
Columnar
They have cilia
Found in lining of trachea
What is cartilage
A connective tissue
What type of cells are in cartilage
Chondrocyte cells embedded in a an extra cellular matrix
What is the purpose of cartilage
Stops bones from rubbing and causing damage
Describe the structure of xylem tissue
Dead hollow cells
Lignified cell Walls (waterproof & strong)
Hollow elongated tubes connected
No end walls
Describe the structure of phloem tissue
Siege tube elements are joined end to end
Not a vessel
Not continuous
What does the phloem tissue transport
Sucrose and amino acids
Which plant tissue is there no organelles in
Xylem tissue
What is the function of lignin
Gives strength to support xylem vessel and plant stem stops to collapse
Impermeable to water stops loss of water from vessels
What is an advantage of indulgence being open ended
Allows transport of water and minerals
What process is in the phloem vessels
Translocation
Describe the companion cells
Controls the movement of solutes and provides ATP for active transport into the siege tube elements
Phloem vessels
What is a system
A group of organs working together for a particular function
Digestive system
Cardiovascular system
