cells (bio) Flashcards
State the structure of cell membrane and its functions
structure:
- phospholipid bilayer
- contains proteins, carb chains and cholesterol attached within phospholipid bilayer
- fluid mosiac model (used to describe structure):
- cell membrane fluid - phospholipid and protein molecules not stationary but move rapidly across surface of the membrane
- cell membrane is a mosiac - many diff protein molecules randomly scattered and embedded throughout phospholipid bilayer
function:
- controls movement of substances in and out of cell
- separates and protects cell from surrounding environment
(only small hydrophobic molecules can pass through)
State the structure of Golgi apparatus and its functions
sturcture:
-stacks of flattenedd membrane-bound sacs
functions: chemically modifies products received from ERs and packages them into vesicles for transport
State the structure of RER and its functions
structure:
- system of flattened membrane-bound sacs
- appears ‘rough’ under electron miroscope because of ribosomes on surface
function:
- protein synthesis (polypeptide chain synthesised by the ribosomes folded in RER)
define tissue
group of similar cells which work together to perform specific function
State the structure of animal vacuoles and its functions
structure:
- fluid-filled sac bound by a single membrane
- formed by either pinching-off part of cell membrane or by enlargement of a vesicle from Golgi apparatus
- may also be formed by phagocytosis
- relatively smaller than plant vacuoles and exist temporarily
function:
- food storage vacuoles store dissolved nutrients
- contractile vacuoles temporarily store excess water (eventually expelled)
State the structure of lysomes and its functions
structure:
- small, spherical vesicles surrounded by single membrane
- contain hydrolytic enzymes such as lipases, proteases and nucleases
function:
- digest materials taken in from outside
- digest worn-out organelles in the cell (will fuse with worn-out organelles, breaking them down –> autophagy)
State the structure of SER and its functions
structure:
- consists of fine tubules
function:
- lipid synthesis
- detoxification of drugs and poisons (esp in liver)
- storage and release of calcium ions
State the structure of plant vacuoles and its functions
structure:
- large central vacuole permanent and takes up >80% of cell volume
- enclosed in a single partially permeable membrane called tonoplast
- filled with cell sap (solution of sugars, ions, waste products, pigments, etc)
function:
- storage of nutrients and ions
- disposal sites for metabolic by-products
- may contain pigments that colour cells
state what cytoplasm contains
cytosol: aqueous solution of essential ions, soluble proteins and soluble organic compounds (e.g. sugars and amino acids)
cytoskeleton: network of protein fibres that give support, motility and regulation to cell
organelles: structures with specialised functions, suspended in cytosol
are leaves a tissue or organ
organ
what is cytoplasmic streaming
movement of fluid substance (cytosol) within plant or animal cell
aids in the transport of materials and organlles around cell
State the structure of chloroplasts and its functions
structure:
- bounded by a double membrane
- contain chlorophyll
- contain thylakoids and stroma
function:
- site of photosynthesis
State the structure of ribosomes and its functions
structure:
- small, round structures found in all cells
- may occur as free ribosomes suspended in cytosol or bound to rough ER
function:
- site of polypeptide synthesis
- free ribosomes generally make proteins that will function within cytosol
- bound ribosomes generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes, or for export from the cell
define cell
building block of life; simplest units that have all the characteristics of life
State the structure of cellulose cell wall and its functions
structure:
- consists of cellulos fibres embed in a polysaccharide matrix
functions:
- provide mechanical support
- resist expansion when water enters by osmosis
describe the function, structural adaptation of a root hair cell and how it relates to its function
absorption of water and mineral salts
presence of long narrow extension (surface area to volume ratio increase -> rate of absorption of water and mineral salts)
large central vacuole (storage of water in the cell)
thin cell wall (reduce distance water and mineral salts need to diffuse
define organ system
several organs working tgt for a common purpose make up an organ system
State the structure of nucleus and its functions
structure:
- usually spherical
- consist of nuclear envelop which separates nucleus from cytoplasm
- contains nucleolus which synthesises ribosomes
- contains DNA
function:
contains hereditary material (DNA) and controls activities of the cells
State the structure of centrioles and its functions
structure:
- small, hollow cylinders that occur in paris
- found in animal cells but absent in plant cells
function:
cell division in animal cells
State the structure of mitochondria and its functions
structure:
- rod-shaped or cylindrical
- bounded by a double membrane
function:
- involved in aerobic respiration –> release energy in the form of ATP (“energy molecule” in living things)
- abundant in metabolically active cells (e.g. muscle and liver cells)
describe the process of protein synthesis and secretion
- polypeptide chains synthesised at ribosomes and folded at RER to form proteins
- transport vesicles containing proteins made by RER pinch off RER
- transport vesiscles fuse and release their substances into Golgi apparatus
- chemically modified in Golgi apparatus
- packaged into secretory vesicles which pinch off Golgi apparatus
- secretory vesicles move towards and fuse with cell membrane, releasing proteins outside cell by exocytosis
describe the process of the formation of lysosome
- lysosomal enzymes synthesised on the rough ER and transported via transport vesicles to Golgi apparatus for chemical modification
- vesicle containing enzymes pinches off Golgi apparatus, forming lysosome
- enzymes must be kept apart from rest of cell or else they wld destroy the cell
describe the function, structural adaptation of a red blood cell and how it relates to its function
transport oxygen
presence of haemoglobin (combines with oxygen)
biconcave shape (increases surface area to volume ratio -> increase rate of diffusion of oxygen)
absence of nucleus (allow more haemoglobin to be packed in the cell -> more oxygen)
describe the structural adaptation of a muscle tissue and how it relates to its function
cells are elongated and cylindrical in shape; contain numerous mtiochondria (provide energy through aerobic respiration for contraction of muscle cells to do work)
