2.1.6 Flashcards
What makes up interphase?
G1
S phase
G2
What are the steps f the cell cycle?
G1
S phase
G2
Mitosis
What is the product of mitosis?
2 daughter cells
genetically identical
What happens in G1?
Cell growth
organelle growth
increase in number of organelles
protein synthesis
What happens in G2?
short gap before mitosis
cell growth
organelle growth
increase in number of organelles
protein synthesis
spindle can begin to form
What is the S phase?
DNA replication
Why does the S phase happen?
to ensure that
the daughter cells have the same/identical DNA and
a full copy of DNA
What is cytokinesis?
cell divides into 2
What is the purpose of checkpoints?
regulating the cell cycle
What is the G0 checkpoint?
cell leaves cycle temporarily / permanently
Why does a cell enter the G0 checkpoint?
the cell has fully differentiated
DNA of cell is damaged so the cell will try to repair the DNA
What is the G1 checkpoint?
Checks if all requirements are met
so that DNA replication can begin
What happens if a problem is detected in a checkpoint?
cell goes to G0
When does the G1 checkpoint happen?
occurs between G1 and S phase
What is the G2 checkpoint?
checks for a mutation in the DNA
Daughter cells might not recieive identical genetic information
proteins might not function
What is the metaphase checkpoint?
metaphase cannot proceed until chromosomes have attached to spindles and are aligned correctly
Why does mitosis occur?
repair of damaged tissues / cells
growth of an organism
What happens to the nuclear envelope in prophase?
breaks down
What happens to the chromosomes in prophase?
condense
What happens to the spindle fibres in prophase?
attach to the centromere on the chromosomes
How do the chromosomes condense?
chromosomes wrap around histones to make them more dense
What happens to chromosomes in metaphase?
chromosomes line up along equator of cell
What happens to spindle fibres in prophase and metaphase ?
attach to the centromere on the chromosomes
What happens to chromatids in anaphase?
chromatids are pulled to opposite poles of the cell
What happens to the centromere in anaphase?
breaks
What do the spindle fibres do in anaphase?
contract
What happens to the nuclear envelope in telophase?
begins to form
What happens to the chromosomes in telophase?
uncoil
What happens to the cell surface membrane in telophase?
undergoes cytokinesis
What happens to spindle fibres in telophase?
break down
What happens in prophase?
nuclear envelope breaks down
Chromosomes condense
spindle fibres attach to the centromere on chromosomes
What happens in metaphase?
Chromosomes line up along equator of cell
spindle fibres attach to the centromere on the chromosomes
What happens in anaphase?
chromatids are pulled to opposite poles of the cell by spindle fibres contracting
centromere breaks
What happens in telophase?
nuclear envelope begins to form
chromosomes uncoil
cell surface membrane undergoes cytokinesis
spindle fibres break down
What does cytokinesis cause in an animal cell?
cleavage furrow
Why do we use the root tip?
mitosis occurs here
Why do we heat the plant sample in acid?
break down the cell wall
Why do we stain the sample?
Provide contrast
make chromosomes more visible
Why is it important to squash the sample?
to make the sample as thin as possible
1 cell thick
so light can pass through
How to calculate mitotic index?
cells in mitosis
/
total number of cells
What is a stem cell?
undifferentiated cell that can differentiate into any type of cell by mitosis
What are totipotent cells?
stem cells that can differentiate into any type of body cell
can form extra-embryonic cells that can make up placenta and umbilical cord
What is the only totipotent cell?
zygote
What are pluripotent stem cells?
stem cells that can form any type of body cell
BUT
cannot form extra-embryonic cells
What are multipotent stem cells?
stem cells that can form more than 1 cell type
BUT not all cell types
What is an exmaple of multipotent stem cells?
adult stem cells
How do stem cells make erythrocytes ?
stem cell from bone marrow
differentiate by mitosis
removes nucleus
create lots of HbHow do
How do stem cells make neutrophils?
stem cell from bone marrow
differentiates by mitosis
stem cell change sshape of nucleus to be lobed
stem cell will need to produce lysosomes
Where is meristem found?
vascular cambium
How do meristem make xylem and phloem?
meristem undergoes differentiation
How is xylem formed?
lignin reinforces and waterproofs wall
provides strength against negative pressure
cell dies
creates a hollow tube
tube limits lateral movement of water
allows adhesion
How is phloem formed?
cells stretch and elongate to form sieve tube elements
has gaps which allow transport of assimilates like sucrose and amino acids
companion cells provide atp
What neurological conditions can stem cells be used to treat?
Alzheimers
Parkinsons
What are the features of RBC?
no nucleus, mitochondria, golgi or RER
packed with Hb
biconcave
How does the features of a RBC aid in their function?
lack of organelles allows erythrocyte to be packed with Hb -> so it can carry a large volume of oxygen
biconcave disk shape of the cell increases surface area: volume ratio so gas exchange is more efficient
What are the features of a neutrophil?
nucleus
cytoplasm appears granular due to enormous numbers of lysosomes
How do the features of a neutrophil aid in it’s function?
lysosomes contain digestive / hydrolytic enzymes that break down engulfed particles
they have a flexible shape which helps them engulf foreign particles / pathogens
What are the features of squamous epithelium cells?
flattened to form a thin, smooth, flat surface
lines tube such as blood vessels
epithelial tissue is held in place by the basement membrane
How do the features of squamous epithelium aid diffusion?
squamous epithelium are very thin and so allow efficient diffusion of gases as there is a short diffusion distance
these cells can be found in lining of lungs
What are ciliated epithelial cells?
column shaped cells
usually on inner surface of tubes
cilia wave in a synchronised rhythm to move mucus
Why do smokers get bad cough?
cilia on cells are damaged and so cant move the mucus that captures particles
What are the features of the sperm cell?
ATP for movement
specialised lysosome in acrosome
shape aids movement
flagellum helps propel the cell
contains half the number of chromosmes
Why is their lysosome in the head of the acrosome?
contains digestive enzymes that allow the sperm cell to penetrate the surface of the egg cell
What are the features of the palisade cell?
long
thin
tightly packed
loads of chloroplasts
spongy mesophyll under palisade have air spaces for circulation
How do the features of the palisade cell aid their function?
absorb a lot of sunlight and perform the most photosynthesis
many chloroplasts increase efficiency of photosynthesis
What are the features of the guard cells and stomata?
allows gas exchange
guard cell son each side that open the stomata and open when turgid and close the stomata when turgid
How do the guard cells become turgid?
take up water by osmosis
thin outer walls and thick inner walls bend the cells to open stomata
What are the features or the root hair cell?
increased SA:V ratio
thin walls
How do the features of a root cell aid in their function?
inc SA:V ration allows greater uptake of water ad minerals
thin walls allow efficient gas exchange
What are tissues?
same type of cell working together for the same function
What are some examples of tissues?
epithelilal tissue
connective tissue
muscle tissue
What is an organ?
groups of different tissues working together for the same function
What does the epithelilal tissue do?
lines the organs
What does the connective tissue do?
adds support and structure
What does the muscle tissue do?
contracts
What are organ systems made of?
different organs
What makes up organisms?
organ systems
What is the role of the squamous epithelium tissue?
allows for a thin diffusion pathway
What is the role of the cillliated epithelial tissue?
wafts mucus to back of the throat
How do squamous and ciliated epithelial cells work together?
aid diffusion of gases / clear airways
What is the role of the cartilage>?
holds the trachea open under negative pressure
What is the role of the muscle tissue?
contracts to constrict the airway
How do muscle tissue and cartilage work together?
they work together in the lungs in controlling ventillation
What is the role of the xylem?
transports water up the plant for transpiration?
What is the role of the phloem tissue?
transports assimilates up and down the plant in translocation
How so xylem tissue and phloem tissue work together?
create vascular bundles in the plant
What are homologous chromosomes?
1 is maternal
1 is paternal
same genes
different alleles
same length
centromere in the same place
What does meiosis produce?
4 genetically different hapolid daughter cells
gamates
Why does the haploid happen?
so that they can form a zygote that is diploid
What happens in prophase I?
chromatin condenses
homolgous chromsomes for a bivalent
nucleolus disappears
spindle forms
crossing over
What happens in anaphase I?
homologous chromosomes in each bivalent are pulled to opposite poles and the bivalent splits
What happens to metaphase 1?
Bivalents line up on equator of cell
independent assortment
What happens in telophase?
2 new nuclear envelopes form
cell divides by cytokinesis
What does crossing over cause?
new combo of alleles
What happens in metaphase 1?
independent assortment
What happens in prophase 2?
Nucleolus dissappears
chromosmes condense
spindle forms
What is metaphase 2?
chromosomes arrange themselves on the equator
attach by centromere to spindle fibres
independent assortment
What is anaphase II?
centromeres divide
chromatids are pulled apart to opposite poles
What is telophase 2?
nuclear envelope reforms around haploid nuclei
cell divides by cytokinesis
