Cell Cycle, Division and organisation Flashcards
What happens in G0
Cells do not replicate, just respire and do normal metabolic reactions
Checkpoints (5)
At the end of each stage, checkpoints confirm if cell is able to progress
G1 checkpoint: cell size, nutrients, growth and DNA damage
G2: cell size, DNA replication, DNA damage
Spindle assembly checkpoint: At the metaphase stage in mitosis, this checks all the chromosomes are attached to spindle fibres
Failure at checkpoints lead to apoptosis.
Apoptosis
Programmed cell death
Homologous chromosomes (5)
- 23 chromosomes from each parent
Same; length Bonding pattern Type of gene Centromere position
Four phases of mitosis
Prophase
Metaphase
Anaphase
Telophase
Prophase (4)
Chromatin condenses to form chromosomes
Chromatids held by centromeres
Nuclear envelope disappears
Centrosomes form spindle fibres
Metaphase (4)
Chromosomes attach to spindle fibres
Motor proteins help with movement
(Protein E in centromere help pull chromosomes into 2)
Chromosomes line down metaphase plate
Anaphase (2)
Motor proteins pull on spindle fibres- s.f shorten
Chromosomes are split to either side of cell
Telophase (2)
Nuclear membrane constructed around chromosomes
Nuclear envelope constructed
Cytokinesis (2)
New cell membrane is formed
Cell splits to form two identical daughter cells
Interphase (name 6 processes that occurs in this phase)
All the processes before mitosis
- genetic material copied
- cell growth
- organelle replication
- ATP production
- proteins synthesis
- checking of DNA
Purpose of mitosis (4)
Cell replacement
Tissue repair
Organism/ tissue growth
Asexual reproduction
Location of mitosis
Every cell but gametes
Product of mitosis
2 genetically identical
diploid daughter cells
Purpose of meiosis
Creates gametes in animals
Creation of spores in fungi and plants
Location of meiosis
Reproductive organs in animals
Product of meiosis
4 haploid daughter cells
genetically unique
Mix of DNA from both parents
Events that occur in G1
Cell growth
Protein synthesis
Organelles duplicate
Transcription
Features and function of neutrophils (4)
Ingests and destroy invading microorganisms
Lobed nucleus; squeeze through small gaps and vessels
Granular cytoplasm; contains lysosomes which release enzymes to attack pathogens
10-14 micro meters
Erythrocytes functions and structure (5)
Carries oxygen in the blood.
Haemoglobin; binds to oxygen
No nucleus; more space for haemoglobin
Bio concave; greater SA:V ratio
Flexible; squeeze through tiny capillaries
Squamous epithelium function and features (2)
Flat, single layered, smooth cells; covers a large area
Basement membrane; collagen and glycoproteins that binds to connective tissue. Used for cell signalling and cell adhesion.
Thin: short distance for diffusion
Ciliated epithelium (4)
Removes particles that shouldn’t be in lungs
Column shaped
Cilia hairs bear in synchronises pattern that help remove dust and other particles
Goblet cells produce mucus to trap dust and etc
Sperm cells (5)
Male gamete in sexual reproduction; delivers genetic information to the ovum
Undulipodium; tail that propels the cell.
Acrosome; lysosomes that penetrate ovum coat leading to fertilisation
Small and thin; Allows easier movement
Many mitochondria: Allows release of energy for movement.
Xylem (4)
Transportation of water and minerals UP plants
Vessel elements; elongated dead cells
Ligin; waterproof walls for dead cells, provides structural support
Wide lumen; space for material and gives tube structure
Phloem (3)
Transportation of organic nutrients up and down plants
Transporta sucrose esp from leaves and stem to where it is needed
Sieve tubes and plates
Palisade cells (5)
In mesophyll(leave cells); contains chloroplast to absorb light for photosynthesis
Rectangular boxes shape; pack tightly in continuous column to Maximise absorption
Large vacuole; turgor pressure, restricting chloroplast to edge of cell
Thin cell walls; quick diffusion of gas for photosynthesis
Cytoplasmic streaming: Movement of fluid inside the cell which moves chloroplast around
Guard cells (5)
Control the stomatal opening
Large vacuole; takes up water and expands to open the stomata.
Unevenly thickened cell wall; allows cell to change shape as it becomes turgid
Mitochondria; ATP for active transport
Active pumps in plasma membrane: Allows mineral ions to be transported in and out of cell to control water potential.
Root hair cells (3)
Long extensions; large surface area for more absorption
Active pumps in plasma membrane: actively absorb minerals ions.
Thin cell wall: Decreases barrier for transport of water and mineral ions.
What is a stem cell (3)
Unspecialised cell
Capable of mitosis
Able to become other cell types
Totipotent potency and examples (3)
Stem cells that can specialise into ANY type of cell
Can produce whole organisms
Eg fertilised eggs, zygotes
Pluripotent potency (3)
Stem cells that can form all tissue types
Can’t form whole organisms
In early embryos
Multipotent potency (3)
Stem cells that form a range of cells
Within a certain type of tissue
Eg haematopoetic cells in bone marrow
Where do all blood cells derive from
Bone marrow
Sources of animal stem cells (2)
Embryonic; totipotent until it becomes a blastocyst
Then is pluripotent until birth
Adult; bone marrow, umbilical cord
Multipotent can be trigger to pluripotent
Advantages of using umbilical cord instead of bone marrow (4)
- less invasive surgery
- more plentiful source
- cannot be rejected from umbilicus owner
- can be stored for later use
Meritstem (5)
Stem cells in plants
Found in growing tissue; tips of root and shoots
Between phloem and xylem- vascular cambium
Differentiation occurs from there
Pluripotent for the lifetime
Vascular cambium (2)
Where meristem tissue is located- between xylem and phloem
Cell differentiation happens from this region
Organ
Collection of tissue adapted to perform certain function in an organism
Eg heart pumps blood
Organ system
Collection of organs working together to carry out a major function
Eg digestive, cardiovascular, gaseous exchange
Tissue
Collection of differentiated cells that have specialised function
Describe the ultra structure of a neutrophil enables it to perform its function (6)
- Lysosomes to secrete enzymes
- Many ribosome, mitochondria, microfilaments and receptor sites
- lots of Golgi
How does plant cell division differ from animal? (3)
- cell wall is between plant cells
- cytokinesis starts from the middle in plants
- only occurs in the meristem in plants
Reduction division
When a cell divides to form a haploid cell from diploid
- first division in Meiosis 1
Propose 1 (5)
- Chromosomes condense
- Homologous chromosomes pair up to form bivalents
- nuclear envelope disintegrates and spindle fibres form
- Crossing over of chromosomes between non-sister chromatids occur at chiasmata
Metaphase 1 (2)
- Chromosomes are lined up at equator by spindle fibres
- Independent assortment of chromosomes sets orientation of maternal/paternal chromosomes to different poles of the cell
Anaphase 1 (3)
- Spindle fibres shorten and break chromosomes by chiasmata
- Recombinant chromosomes formed when crossed over sections join when they are pulled apart
- this forms new combinations of DNA (leads to genetic variation)
Telophase 1(3)
- Chromosomes settle at each pole of the cell and condense
- nuclear envelop reforms
- cell divides at cell equator( formation of cell membrane) via cytokinesis
Prophase 2 (2)
- Chromosomes condense
- nuclear envelope disintegrates whilst spindle fibres form
Metaphase 2
- Chromosomes are lined up by spindle fibres on equator plate
- Independent assortment of chromatids occurs where genetically unique chromatids are orientated at different poles of the cell
Anaphase 2
- Spindle fibres pull apart chromosomes by centromere so each pole has chromatids
Telophase 2 (3)
- Chromosomes uncoil and settle at opposite poles
- nuclear envelope develops
- cytokinesis occurs at the cell equator
How does crossing over cause genetic variation
- non-sister chromatids entangle at the chiasmata
- exchange of alleles occur which produces new combinations of alleles
How does independent assortment cause genetic variation (2)
- Homologous chromosomes orientation in metaphase 1 (chromosomes) and metaphase 2 (chromatids) are independent
- formation of new combinations of alleles occur due to assignment of chromosomes to individual cells
Importance of creating genetic variation in meiosis (3)
- Genetically diverse population is important for natural selection
- Allows opportunity for individuals to obtain traits that may be beneficial in a changing environment
- no variation would mean that the population would be vulnerable to selection pressures and there would be no opportunity for adaptations
