CELL DIVISION Flashcards
what is the cell cycle
a highly ordered sequence of events that takes place in a cell, resulting in division of the cell and the formation of two genetically different daughter cells
what is interphase
a period of growth and normal working separate divisions, cell spends most of its time there
what are the three stages of interphase
G1, S, G2
what happens in the G1 stage
the first growth phase: proteins from which organelles are synthesised are produced and organelles replicate. the cell increases in size
what happens in the synthesis stage of interphase
DNA is replicated in the nucleus
what happens in the G2 stage of interphase
the second growth phase, the cell continues to increase in size, energy stores are increased, and the duplicated DNA is checked for errors
what are the stages of the mitotic phase
mitosis and cytokinesis
what is the GO phase
the name given to the phase when the cell leaves the cell, permanently or temporarily, because of differentiation, cell DNA damaged
what is mitosis needed for
asexual reproduction, growth and repair, genetically identical daughter cells
what happens during prophase
chromatin condenses into chromosomes, nucleolus disappears and nuclear membrane breaks down, centrioles migrate to opposite poles
what happens during metaphase
the chromosomes re moved by the spindle fibres to the metaphase plate
what happens during anaphase
chromosomes are split at there centromeres into two separate chromatids which move to the opposite poles of the cell
what happens during telophase
the nuclear envelope reforms, the chromosomes decondense, cytokinesis begins
what different happens in prophase 1
homologous chromosomes pair up, forming bivalents, chromosomes are moved around causing crossing over of chromatids
what different happens in metaphase 1
the homologous pairs of chromosomes line up along the metaphase plate, random orientation causes variation called independent assortment
how is anaphase 1 different
homologous chromosomes are pulled apart and the chromatids stay together, sections of DNA become entangles resulting in exchange of DNA, forms recombinant chromatids
how is metaphase 2 different
more independent assortment and genetic variation, individual chromosomes assemble on metaphase plate
how are RBD adapted to their function.
flattened bioconcave shape to increase SA:V. No nuclei or many other organelles to increase space for haemoglobin, flexible to squeeze through capillaries
how are neutrophils adapted to their role
multi-lobed nucleus, which makes it easier to squeeze through small gaps. Granular cytoplasm contains many lysosomes that contain enzymes used to attack pathogens
how are sperms adapted to their role
flagellum, so are capable of movement, contain many mitochondria to supply energy needed to swim, acrosome on the head of sperms contains digestive enzymes which are released to digest protective layers around the ovum and allow sperms to penetrate
how are palisade cells adapted to their role
contain chloroplasts to absorb large amounts of light for photosynthesis, rectangular box shape allows for them to be closely packed together, thin cells walls increasing rate of diffusion of CO2 large vacuous to maintain turgor pressure, chloroplasts can move within cytoplasm to absorb more light
hare root hair cells adapted to their function
root hairs to increase surface area of cell to maximise water and mineral uptake from the soil
how are guard cells adapted to their function
change shape when lose water as a result of osmotic forces, closes stoma to prevent further water loss, cell wall of a guard cell is thicker on one side so the cell doesn’t change shape symmetrically as its volume changes
how is squamous epithelium adapted to its function
one cell thick for rapid diffusion, forms lining of the lungs
how are ciliated epithelium adapted for their function
cilia that move in a rhythmic manner to sweep away substances such as mucus, goblet cells release mucus to trap unwanted particles
how is cartliga adapted to its function
contains fibres of the proteins elastin and collagen so is firm and flexible, prevents bones from rubbing and causing damage
how is muscle adapted for its function
skeletal muscle fibres contain myofibrils which contain contractile proteins
how is the epidermis adapted to its function
covered by a waxy, waterproof cuticle to reduce loss of water, stomata present to allow CO2 in and out, and water vapour and oxygen in out
how is the xylem tissue adapted to its function
walls of the dead cells are strengthened with lignin which provides structural support
how is the phloem tissue adapted to its function
composed of columns of sieve tube cells separated by perforated walls called sieve platesb
what are totipotent stem cells
can differentiate into any type of cell and also extra-embryonic tissues like the amnion and umbilicus e.g fertilised egg cell
what are pluripotent stem cells
can form all tissue types but not whole organisms, present in early embryos and are the origin of the different types of tissue within an organism
what are multipotent stem cells
can only form a range of cells within a certain type of tissue
what diseases could be treated with stem cells
heart disease, type 1 diabetes, parkinsons disease, alzheimers disease, macula degeneration. birth defects, spinal injuries,
