topic 1: cell biology Flashcards
cell theory principles
- all living things are composed of cells
- cells are the smallest unit of life
- cells only arise from pre-existing cells
metabolism
all chemical reactions that take place in a cell
response
respond to stimuli, such as light and temperature
homeostasis
keeps a stable internal environment (cell conditions)
growth
grow/change in size
reproduction
asexual/sexual
excretion
the removal of metabolic waste, such as salt and co2
striated skeletal muscle
challenges idea that cells have 1 nucleus (multinucleated)
aseptate fungal hyphae
challenges the idea that cells are a single unit
giant algae (acetabularia)
challenges idea that cells are small
magnification
size of image divided by actual size of object
actual size of object
size of image divided by magnification
large SA:V ratio
cell can act more efficiently
benefits of SA:V
diffusion pathways are shorter and concentration gradients are easier to generate
total surface area
height x width x number of sides x boxes
total volume
height x width x length x boxes
SA:V ratio
surface area divided by volume
emergent properties
arise from the interactions of component parts of complex structures
stem cells
are specialised cells that can continuously divide and replicate and can differentiate into special cell types
prokaryotes
circular and naked DNA found in the nucleoid, 70s ribosome size, no membrane organelles present, peptidoglycan in the cell wall. reproduce by binary fission
eukaryotes
linear DNA that is associated with proteins found in the nucleus, 80s ribosome size, membrane organelles present, cellulose in the cell wall.
amphipathetic
molecule that possesses both hydrophobic and hydrophilic elements, found in the phospholipids of biological membranes
phospholipid molecules
contain polar phosphate heads and non-polar lipid tails
integral proteins
permanently attached to the membrane and are typically transmembrane
peripheral proteins
temporarily attached and associate with one surface of the cell membrane
glycoproteins
proteins with ogliosaccaride chain attached. important for cell recognition by the immune system.
cholesterol
makes the phospholipids pack more tightly and regulates the fluidity and flexibility of the membrane
membrane fluidity
the hydrophobic hydrocarbon tails usually behave as a liquid. Hydrophilic phosphate heads act more like a solid
diffusion
movement of liquids and gases from high to low concentration down the partially permeable membrane
osmosis
movement of water molecules from high to low concentration through a semipermeable membrane
facilitated diffusion
uses a channel protein to a assist with transportation of polar molecules from high to low concentration
osmotic control
pass through the plasma membrane from an area of low solute (high water) concentration to high solute (low water) concentration.
prevents damage to cells and tissues
pumps
transport larger polar substances or ions using a carrier protein
sodium potassium pump
cycle of sodium ions being pumped out of the membrane and potassium ions being pumped in. this uses 1 ATP
integral protein pumps
uses the energy from hydrolysis of ATP to move ions or large molecules across the cell membrane, against the concentration gradient
vesicles
carry proteins produced by ribosomes on the rER to the Golgi apparatus where they are prepared for export from the cell via another vesicle
endocytosis
taking in of external substances by inward pouching of the plasma membrane, forming a vesicle- without crossing the membrane
exocytosis
the release of substances from a cell when a vesicle joins with the plasma membrane- without crossing the membrane
muler and Urey experiment
recreated conditions of the early earth to demonstrate chemical evolution.
endosymbiotic theory
explains the existence of several organelles of eukaryotes.
when is mitosis required
growth, asexual reproduction, tissue repair, embryonic development
cell cycle
series of events through with cells pass to divide and create two identical daughter cells
growth & mitosis
increases in size by increasing number of cells
asexual reproduction & mitosis
eukaryotic organisms reproduce asexually
tissue repair & mitosis
damaged tissue can recover by replacing damaged cells
embryonic development & mitosis
a fertilised egg undergoes mitosis to develop into an embryo
interphase
consists of the parts of the cell cycle that don’t involve cell division
G1
increases volume of cytoplasm, growth, organelles produced, proteins synthesised, normal activity of the cell
S (synthesis)
DNA is replicated
G2
preparation for mitosis, more growth
functions of cells during interphase
metabolic reactions, protein synthesis, organelle numbers are increased, DNA is replicated
centrioles
organise spindle microtubules
centromere
part of the chromosome that links sister chromatids
sister chromatids
duplicated chromosomes attached by a centromere
prophase
the centrosomes move to opposite poles of the cell and spindle fibres begin to form between them. DNA supercoils and chromatin condenses and becomes sister chromatids. The nuclear membrane is broken down and disappears
metaphase
spindle fibres from each of the two centrosomes attach to the centromere of each pair of sister chromatids. Contraction of the microtubule spindle fibres cause the sister chromatid to line up along the centre (equator) of the cell
anaphase
continued contraction of the microtubule spindle fibres cause the separation of the sister chromatids. the chromatids are now referred to as chromosomes. chromosomes move to the opposite poles of the cell
telophase
chromosomes arrive at the poles. microtubule spindle fibres disappear. New nuclear membranes re-form around each set of chromosomes. the chromosomes uncoil and de-condense to chromatin
cytokinesis
the division of the cytoplasm
cytokinesis in animals cells
a ring of contractile protein inside the plasma membrane at the equator pulls the plasma membrane inwards. the inward pull on the plasma membrane produces the characteristic cleavage furrow. When the cleavage furrow reaches the centre of the cell, it is pinched apart to from 2 daughter cells
cytokinesis in plant cells
membrane enclosed vesicles derived from the Golgi apparatus migrate to the centre of the cell. vesicles fuse to form tubular structures. the tubular structures merge to form 2 layers of the plasma membrane. the cell plate continues to develop until it connects with the existing cells plasma membrane. This completes the division of the cytoplasm and the formation of 2 daughter cells. Vesicles deposit, by exocytosis, pectins and other substances in the lumen between daughter cells to form the middle lamella. both daughter cells secrete cellulose to form their new adjoining cell walls
cyclins
are a family of proteins that control the progression of cells through the cell cycle
mutation
a change in an organisms genetic code. A mutation of a certain gene can cause cancer
mutagen
are agents that cause gene mutations. not all mutations result in cancers, but anything that causes a mutation has the potential to cause cancer
factors that increase the probability of tumour development
- vast number of cells in a human body
- the longer life span the greater chance of mutation
