Cell Structure and Organisation Flashcards
what are cells?
building blocks of life
what is protoplasm?
mass of living matter consisting of cell membrane, cytoplasm and nucleus
what are 3 characteristics of the cell membrane?
1) surrounds cytoplasm
2) partially permeable, allows only small soluble substances to pass through (becomes more permeable upon heating)
3) primarily made up of phospholipids (lipid bilayer) and proteins
what is the function of the cell membrane?
controls movement of substances in and out of the cell
what is a characteristic of the cytoplasm?
found between cell membrane and nucleus
what are the 2 functions of the cytoplasm?
1) site of cellular activities
2) contains specialised structures called organelles
what are 2 characteristics of the cell wall?
1) made up of cellulose
2) fully permeable (osmosis does not occur through cell wall)
what are the 2 functions of the cell wall?
1) provides mechanical support and protects cell from injuries
2) gives cell a fixed shape
what are 2 characteristics of the nucleus?
1) individual parts can only be seen under an electron microscope
2) cells without nucleus cannot divide
what are the 2 functions of the nucleus?
1) controls cellular activities (e.g. cell growth, reproduction, reparation of cells)
2) essential for cell division
what are the 2 characteristics of chromosomes?
1) long thread-like structure found within nucleus
2) condenses into thick, rod-shaped like structures during cell division
what is the function of chromosomes?
made up of deoxyribonucleic acid (DNA) which carries hereditary information
what is the function of the nuclear membrane (surround nucleus)?
separates contents of nucleus from rest of the cytoplasm
what are the 3 characteristics of the rough endoplasmic reticulum (RER)?
1) network of flattened spaces lined with membrane (filled with fluid)
2) outer surface is continuous with nuclear envelope
3) rough surface due to ribosomes studded on surface
what is the function of the rough endoplasmic reticulum (RER)?
transports proteins made by ribosomes to the Golgi apparatus
what are the 2 characteristics of ribosomes?
1) small round structures
2) either attached to RER or lie freely in cytoplasm
what is the function of ribosomes?
synthesise proteins
*those attached to RER usually make proteins transported out of cell
*those lying freely in cytoplasm make proteins used within cell
what is the characteristic of the smooth endoplasmic reticulum (SER)?
more tubular than RER and no ribosomes attached to surface
what are the 3 functions of the smooth endoplasmic reticulum (SER)?
1) synthesises lipids and steroids
2) involved in detoxification
3) gives rise to Golgi bodies
what is the characteristic of the Golgi apparatus/body?
consists of flattened spaces surrounded by membranes
what are the 2 functions of the Golgi apparatus/body?
1) chemically modifies ER products
2) stores and packages substances in vesicles for secretion out of cell
what is the characteristic of the mitochondria?
oval/sausage-shaped organelles
what is the function of the mitochondria?
release energy in the form of adenosine triphosphate (ATP) during cellular respiration for growth, cell division and active transport
what is the characteristic of chloroplasts?
oval structures in plant cells
what is the function of chloroplasts?
contains green photosynthetic pigments called chlorophyll required to trap sunlight for photosynthesis to occur
what is the characteristic of a vacuole?
fluid-filled space (cell sap) surrounded by a partially permeable membrane (tonoplast)
what is the function of a vacuole?
store substances within cell
what is the difference between vacuole(s) in plant and animal cells?
plant cells: one large central vacuole consisting of substances such as water, sugars, mineral salts, amino acids (cell sap)
animal cells: numerous small temporary vacuoles that store water and food substances
what are 3 differences between plant and animal cells?
plant cells:
1) have cell wall
2) have a large central vacuole
3) have chloroplasts
animal cells:
1) no cell wall
2) numerous small temporary vacuoles
3) no chloroplasts
what is differentiation?
process by which a cell becomes specialised for a specific function
what are 4 adaptations of red blood cells (erythrocytes)?
1) contains haemoglobin
2) circular biconcave shape
3) absence of nucleus (enucleate)
4) flexible
why do red blood cells contain haemoglobin?
binds to oxygen and transports it around the body
why do red blood cells have a circular biconcave shape?
(because it is enucleate) increases surface-area-to-volume ratio for an increased rate of oxygen absorption and release
why are red blood cells enucleate?
allows for packing of more haemoglobin for transport of oxygen around the body
*however, cell division cannot occur
why are red blood cells flexible?
to easily squeeze through capillaries
what are 3 adaptations of muscle cells (myocytes)?
1) contain numerous mitochondria
2) has contractile protein fibres
3) have many nuclei
why do muscle cells contain numerous mitochondria?
provide energy for contraction of muscle cell
why do muscle cells have contractile protein fibres?
they contract and relax to bring about movement
why do muscle cells have many nuclei?
to allow for cell division
what are 2 adaptations of root hair cells?
1) long and narrow elongation
2) maintains lower water potential in vacuole (as cell sap is very concentrated)
why do root hair cells have a long and narrow elongation?
increases surface-area-to-volume ratio for an increased rate of absorption of water and mineral salts
why do root hair cells maintain lower water potential in their vacuole?
allows water to enter the cell via osmosis
