C6 - Cell division Flashcards
Whats the difference between meiosis and mitosis
sexual VS asexual reproduction
variation VS no variation
4 cells VS 2 cells
crossing over VS no crossing over
haploids VS diploids
gametes VS other cells created
differences between plant cell division and animal cell division
centrioles VS no centrioles
cell plated form VS animal burrows
where does cell division happen in plants
Meristems
Explain how meiosis results in genetic variation.
crossing over - prophase I
Independent assortment - Metaphase I &2
section of DNA swapped between sister chromatids
Discuss the ways in which genetic variation is produced, including the role of nuclear division.
independent assortment of homologous chromosomes Metaphase I- randomly arranged across the equator
Homologous chromosomes have different allele
crossing over prophase = more crossing over points the more variation-> new combination of alleles
mutation - changes in DNA if they’re not picked up in checks
Two phases of the cell cycle are
G1 and G2. Outline the processes that take place in these two phases.
G1
(more) protein, synthesised / made;
(more) cytoplasm volume increases;
cell, grows / increases in size;
(more) organelles, produced / grow and
divide / replicate
G2
(more) organelles, produced / grow and
divide / replicate;
energy stores, increase / AW;
idea of (DNA) proofreading / checkpoint;
What happens in the S-phase
DNA replicates
allowing for the 2 daughter cells to be identical
What makes up interphase
G1
G2
S
Explain what G0 is and why cells may enter this stage
Resting phase - when the cell isn’t active
cells leave :
differentiated
the cell will try and repair the DNA
senescent- the cells too old to divide anymore
State the roles of the different checkpoints
G1 - cell size and damage
G2- check for mutation , cell size and damage
Spindle checkpoint - check if spindle fibres are aligned properly &if the chromosomes are attached
What’s the significance of mitosis (3)
Growth of organisms
Repair of damages tissues
Asexual reproduction
What’s the role of histones in Mitosis
For the chromosomes to wrap around so they can be condensed and appear more visible
Define Homologous chromosomes
One maternal and one paternal chromosomes that have the same genes but different alleles of the same length with the centromere in the same place
Why do gametes have to be haploids
So they can form a diploid zygote
Explain the stages of mitosis
PROPHASE - nuclear envelope breaks down , chromosomes condense ,centrioles begin to form
METAPHASE - chromosomes align at the equator
ANAPHASE- centromere splits, each chromosome is pulled to opposite poles of the cell, done via the contracting of the cytoskeleton
TELOPHASE - Nuclear envelopes form , chromosomes uncoil and uncondensed , cell surface membrane undergoes cytokines and the spindle fibres break down
Explain the stages of Meiosis I
PROHASE 1 - Chromosomes condense , nuclear envelope breaks down and spindle fibres form . CROSSING OVER AT THE CHAISMATA FORMING A BIVALENT
METAPHASE 1- Chromosomes align at the equator and undergo INDEPENDENTT ASSORTMENT
ANAPHASE 1 - Chromosomes are pulled apart to the poles of the cell
TELOHASE 1-Nuclear envelopes form , chromosomes uncoil and uncondensed , cell surface membrane undergoes cytokines and the spindle fibres break down 2 HAPLOID DAUGHTER CELLS - GENTICLALLY DIFFERENT
Explain the stages of Meiosis 2
PROPHASE 2 - Chromosomes condense , nuclear envelope breaks down and spindle fibres form .
METAPHASE 2- Chromosomes align at the equator and undergo INDEPENDENTT ASSORTMENT
ANAPHASE 2 - Chromosomes are pulled apart to the poles of the cell , CENTROMERE SPLITS
TELOPHASE 2-Nuclear envelopes form , chromosomes uncoil and uncondensed , cell surface membrane undergoes cytokines and the spindle fibres break down 4 HAPLOID DAUGHTER CELLS - GENTICLALLY DIFFERENT
Explain the functions and adaptations of erythrocytes
BICONCAVE - increases SA:VOL = more efficient gas exchange
NO NUCLUES - allows fore more haemoglobin to be inside the cell
HAEMOGLOBIN - allows for o2 to bind
FLEXIBLE - can squeeze through the narrow capillaries
allow for the transport of oxygen
Explain the functions and adaptations of neutrophils
type of WBC-
multi lobed nucleus helps with movement
contain lysosomes - hydrolyse pathogens
Explain the functions and adaptations of squamous epithelium
cover cells
1 cell thick - thin diffusion pathway
flattened
Explain the functions and adaptations of ciliated epithelium
in trachea and bronchi –> clear airways
- goblet cells secrete mucus to trap microorganisms
- hair like structures waft cilia in a rhythmic manner
Explain the functions and adaptations of sperm cells
Gamete Acrosome-digestive enzymes Mitochondria - ATP for movement Streamline Flagellum - aid movement
Explain the functions and adaptations of palisade cells
Chloroplast -photosynthesis
Has layers
Thin wall - easy diffusion
Vacuole-maintain turgor pressure
Explain the functions and adaptations of guard cells
on stomata or gas exchange
- controlling opening and closing
- thinner inner walls and thicker outer walls - bending of walls to open
Explain the functions and adaptations of root hair cells
absorbs ions and water from the soil
- increased SA
- mitochondria - ATP for active transport
- Thin walls - efficient exchange
What are 4 types of tissues
epithelial -lines organs
connective - support
muscle-contraction
nerve-conduct electrical activity
What 2 tissues are involved in controlling ventilation
Cartilage- crings which hold airways open
smooth muscle - constrict airways
define tissues
Group of cells working together to carry out the same function
Define stem cells
undifferentiated cells that can specialise and differentiate into any type of celll
Totipotent
Stem cells that can differentiate into placental and embryonic stem cells , as well as any other type of cell
Pluripotent
Stem cells which can differentiate into any type of cells but not embryonic or placental cells
Multipotent
Stem cells which can turn into a limited range of cells
What are sources of stem cells in humans - what cells can be made from them
Bone marrow - red blood cells and neutrophils
Adult stem cells
What are sources of stem cells in plants -what cells can be made from them
Meristem - cambium
any type of cell
plant stem cells an change into any cell over the course of its life
What diseases can stem cells treat
Alzheimer’s - produce dopamine
Parkinson’s -nerve cells
