The Cell Flashcards
Molecules combine to form
cells
groups of similar cells
tissue
different tissues join together to form
organs
Related organs with a common function form
organ system
all cells arise via
cell division
describe the plasma membrane - 2 points
thin but sturdy/flexible barrier, fluid mosaic model - phospholipids (heads = phosphates, tails = fatty acids) and proteins
Integral proteins
embedded across whole membrane, some = channels for transporting substances, others = chains of carbs to identify and respond to dangerous cells
Peripheral proteins
loosely attach to membrane, easily separated
Role of plasma membrane - 4 points
separates internal parts of cell from external environment, facilitates contact with other cells/substances, receptors for hormones/chemicals/ABs, selective barrier - substances in and waste out
factors affecting permeability - size of mols
large (proteins) = unable to pass through, small (water/AAs) = can
factors affecting permeability - solubility in lipids
dissolve easily (o2) = readily pass through because mainly lipid molecules
factors affecting permeability - charge on ions
ions = opposite charge to membranes and are therefore attracted to it and pass through easily, ion of same charge = repelled
factors affecting permeability - presence of carrier molecules
integral proteins attract and transport substances regardless of size/ability/charge
4 Passive processes
diffusion/osmosis/filtration/dialysis
An active process
use of ATP
ATP stands for
Adenosine Triphosphate
Describe nucleus and explain role of nucleus - 3 points
largest structure in cell, double nucleus membrane - with pores to allow passage in/out and for communication with ER in cytoplasm, contains all genetic material for cell growth/division/reproduction
Describe nucleolus and explain role of nucleolus - 5 points
spherical, composed of RNA/protein, where DNA is found, appears threadlike = chromatin, then shortens during cell division and coils = chromosomes
Describe the cytoplasm - 2 points
thick/elastic fluid, site of chemical reactions and synthesis of new substances
Role of cytoplasm - 3 points
facilitates excretion of waste, contains cytoskeleton - network of microfilaments/microtubules providing support/shape - also allows movement of entire cell and structures in cytoplasm
Describe and explain role of ribosomes - 2 points
found attached to outer surface of nuclear membrane/ER, site of protein synthesis - used/exported
Describe the 2 types of ER (Endoplasmic Reticulum)
Granular - contains ribosomes, Agranular - no ribosomes
General Role of ER - 3 points
allows exchange/transport of material in cell, provides surface for chemical reactions, storage area for synthesised molecules
Describe role of Granular ER - 2 points
processes/sorts proteins, synthesises/packages proteins with Golgi Apparatus
Describe role of Agranular ER - 2 points
network of tubules, synthesises lipids/glycogen/steroids
Describe and explain role of Golgi Apparatus - 3 points
4-8 flattened sacs = cristernae, found close to nucleus and Granular ER, process/sort/deliver proteins
Describe mitochondria - 3 points
smooth outer surface, inner folds = cristae - provide increased surface area for chemical reactions
Explain role of mitochondria - 3 points
produces ATP (stores energy for cellular activities) during aerobic respiration, found in large numbers where there are active cells, able to self-replicate when an increase of ATP is required
Describe a centrosome - 3 points
located near nucleus, contains a pair of centrioles, made up of micro-tubule triplets and protein tubulin
Explain role of centrosome - 2 points
organising centre for growth of mitotic spindle, critical for/in cell division and reproduction
Describe lysosomes - 2 points
membrane-enclosed spheres, form from Golgi apparatus
Explain role of lysosomes - 4 points
the cells digestive system - contains digestive enzymes which break down complex molecules, digest bacteria, break down damaged cells (autolysis)
Describe and explain role of a vacuole - 3 points
storage bubble, mass of fluid surrounded by membrane, stores nutrients/waste products
Describe and explain role of flagella - 3 points
projections from cell surface, contains cytoplasm and bound by plasma membrane, co-ordinated movement causes steady movement across its surface (e.g. ciliated cells move mucus with trapped bacteria from respiratory tract)
Explain the purpose of cell division - 2 points
for growth, to replace damaged/diseased/worn out cells
2 types of cell division
somatic and reproductive
cell division involves 2 types of division -
nuclear and cytoplasmic
sex cells
gametes
