the ultrastructure of eukaryotic cells: membrane- bound organelles Flashcards
what cells are eukaryotic?
all animal, plant, fungal and protocist cells
what is the nucleus surrounded by?
a nuclear envelope
what does the nucleus contain?
DNA organised / wound into linear chromosomes
where is the nucleolus
inside the nucleus
what does the nucleolus contain?
RNA, where chromosomes unwind (uncoil)
what is the nucleolus involved in making?
ribosomes
what is the cytoskeleton?
network of protein filaments within the cytoplasm that move organelles from place to place with the cell
name two examples of protein filaments for the cytoskeleton
1- actin
2- microtubules
what does the cytoskeleton allow cells to do?
to move
name two cell examples cytoskeletons allow to move
1- amoebae
2- lymphocytes
what does the cytoskeleton allow muscle cells to do?
contract
all animal, plant, fungal and protocist cells also have a plasma membrane. what are the other 2 names of this?/ what is the function of it?
1- cell surface membrane
2- cytoplasmic membrane
/ transports nutrients into cell/ transports toxic substances out of cell
other than the nucleus what other membrane- bound organelles do eukaryotic cells contain?
- mitochondria ,
- Golgi apparatus
- endoplasmic reticulum
- small vesicles
do ribosomes have membranes?
no
what is assembled in the ribosomes?
proteins
what happens to organelles in the cytoplasm?
organelles are suspended (spread)
what are cells?
the fundamental units or building blocks of all living organisms
why do cells become specialised?
to do particular jobs
what’s within every cell?
various organelles, each having specific functions
what does a cell having various organelles provide?
a division of labour (work) which means every cell can carry out its many functions efficiently
are most organelles within eukaryotic or prokaryotic cells membrane bound?
eukaryotic cells
what does it mean when organelles are membrane-bound?
covered by a membrane (similar in structure to the plasma membrane of cell surface membrane
why are organelles in eukaryotic cells membrane- bound?
keeps the organelle separate from the rest of the cell, so it is a discrete compartment
do prokaryotic cells have membrane- bound organelles?
no
when it comes to membrane- bound membranes what has electron microscopy enabled scientists to do?
ascertain (discover) the structure of these organelles by making/ examining several sections through an organelle to build a 3D picture of it
when it comes to membrane- bound organelles, what has biochemistry research enabled scientists to do?
find the function of each organelle
what is the nucleus surrounded by?
a double membrane, called the nuclear envelope
what’s the structure like in a nuclear envelope?
there are pores
does the nucleolus have a membrane around it?
no
what acid does the nucleolus contain?
RNA (ribonucleic acid)
what is chromatin?
a genetic material, consisting of DNA wound around histone proteins
when the cell is not dividing, what happens to chromatin?
spread out or extended
when the cell is about to divide, what does chromatin do?
condenses/coils tightly into chromosomes
what do chromosomes make up?
nearly all the organism’s genome (genetic material)
what does the nuclear envelope do?
separates contents of nucleus from rest of cell
in some regions, what happens between the outer and inner membranes?
they fuse together
when the inner and outer nuclear membranes fuse together, what does this enable to happen?
dissolved substances/ ribosomes can pass through
what do the pores in the nuclear envelope enable to leave the nucleus ?
large substances such as messenger RNA (MRNA) to leave nucleus
what do the pores in the nuclear envelope enable to enter the nucleus?/ from where are these coming from?
substances such as steroid hormones coming from the cytoplasm
what is made in the Nucleolus?
ribosomes
what do chromosomes contain?
organism’s genes
the nucleus is the ——- center of the cell. fill in the gap
control
what does the nucleus store?
organism’s genome
what does the nucleus transmit?
genetic information
what does the nucleus provide information for?
protein synthesis
what does the Golgi apparatus consist of?
membrane- bound flattened sacs
what brings materials to and from the Golgi apparatus?
secretory vesicles
what does the Golgi apparatus firstly do to proteins?
modify them
what is added to proteins by the Golgi apparatus to make glycoproteins?
sugar molecules
what is added to proteins by the Golgi apparatus to make lipoproteins?
lipid molecules
what can the Golgi apparatus do to the shape of proteins?
fold them into their 3D shapes
what 3 shapes can mitochondria be?
- spherical
- rod- shaped
- branched
how long are mitochondria ?
2-5 lum
What are mitochondria surrounded by?
two membranes with fluid filled space between them
what is the inner membrane of the mitochondria highly folded onto?
cristae ( inner folds of mitocholdria)
what is the structure of the inner part of the mitochondria?
fluid- filed matrix (spaces within inner membrane)
what are mitochondria the site of?
ATP ( energy production) during aerobic respiration
mitochondria are self ———-. fill in the gap.
replicating
what’s the reason mitochondria are self replicating?
more can be made if the cell’s energy needs to increase.
mitochondria are abundant (rich) in cells where what activity takes place?
metabolic activity (chemical reactions so you can survive)
name two examples of where metabolic activity takes place.
- in liver cells
- at synapses between neurones
what is the Soft endoplasmic reticulum (SER)?
a system of membranes, consisting of fluid- filled cavities (cisternae) that are continuous with the nuclear membrane
what isn’t on the surface of the Soft endoplasmic reticulum (SER)?
ribosomes
what does SER contain?
enzymes
what do the enzymes in SER do?
catalyse (speed up) reactions involved with lipid metabolism
name 4 examples of reactions involved with lipid metabolism by enzymes in the SER
- Synthesis of cholesterol
- Synthesis of lipids/ phospholipids needed by cell
- synthesis of steroid hormones
- involved in absorption, synthesis/ transport of lipids (from gut)
what is the Rough endoplasmic reticulum (RER)?
System of membranes containing fluid- filled cavities (cisternae) that are continuous with the nuclear membrane
what is the Rough endoplasmic reticulum (RER) coated with?
ribosomes
RER is the intracellular ——— system. fill in the gap.
transport
in the RER, what do the cisternae form ?/ what do these do?
channels for transporting substances from one area of the cell to another
what does the RER provide a large surface area for?
ribosomes
what do ribosomes do?
assemble amino acids into proteins
once the proteins have been assembled, what do they then actively pass through then into?
the membrane into the cisternae
once the proteins pass through the membrane then into the cisternae, where are they then transported to and for what?
the Golgi apparatus for modification and packaging
are chloroplasts large or small or large organelles?
large
how long are chloroplasts?
4-10 lum long
what cells are chloroplasts only found in?
plant cells
besides only being in plant cells, chloroplasts can be found in some what?
proticists
what are chloroplasts surrounded by?
a double membrane or envelope
what is the inner membrane of chloroplasts continuous with?
stacks of flattened membrane sacs
what are the stacks of flattened membrane sacs in the inner chloroplast called?
thylakoids (reassembling piles of plates)
what do thylakoids contain?
chlorophyll
what is each stack or pile of thylakoid called?
a granum (plural: grana)
what is the fluid - filled matrix (gap) in the chloroplast called?
the stroma
what do chloroplasts contain loops of?
DNA
what do chloroplasts contain grains of?
starch
what process are chloroplasts the site of?
photosynthesis
what happens to light energy in the first stage of photosynthesis
trapped by chlorophyll
when light energy is trapped by chlorophyll, what is it then used to make ?
ATP (energy currency)
where in the chloroplast does the first stage of photosynthesis occur?
in the grana
what happens to water in the first stage of photosynthesis?/ why?
split to supply hydrogen ions
in the second stage of photosynthesis, what does hydrogen reduce?
carbon dioxide
in the second stage of photosynthesis, what does hydrogen use to reduce carbon dioxide?
ATP (energy currency)
in the second stage of photosynthesis, when carbon dioxide is reduces by hydrogen using ATP , what is made?
carbohydrates
where in the chloroplasts does the second stage of photosynthesis occur?
in the stroma
what plant cell example are chloroplasts abundant (rich ) in ?
leaf cells
where in leaf cells are chloroplasts particularly found in?
palisade mesophyll layer
after proteins are modified in the Golgi apparatus, what are they then packed into?
vesicles
what then happens to the vesicles containing the modified proteins?
pinched off
after the modified proteins are stored in the vesicles, where are they then stored?
in the cell
besides being stored in the cell where else can the modified proteins be moved by the vesicles?
plasma membrane , either to be incorporated into plasma membrane or exported outside cell
the vacuole is surrounded by a membrane called what?
tonoplast
what does the vacuole contain?
fluid
only what cells have a large permanent vacuole?
plant cells
what two things is the vacuole filled with?
water and solutes
what is the function of the permanent vacuole?
maintains cell stability
how does the permanent vacuole maintain cell stability?
when full it pushes against cell wall, making the cell turgid (swollen from being so full)
if all plant cells are turgid, what does this help with?
supporting the plant, especially in non- woody plants
what are lysosomes?
small bags, formed from Golgi apparatus
what is each lysosome surrounded by?
a single membrane
what do lysosomes contain?
powerful hydrolytic (digestive) enzymes
what type of cells are lysosomes abundant in?
phagocytic cells
name two phagocytic cell examples which are types of white blood cell
- neutrophils
- macrophages
what do phagocytic cells do?
ingest/ digest invading pathogens such as bacteria
what’s the function of lysosomes?
keep powerful hydrolytic enzymes separate from rest of cell
what can lysosomes engulf?
old cell organelles/ foreign matter (doesn’t belong in body)
after engulfing old cell organelles and foreign matter what can lysosomes then do to them?
digest them and return the digested components to cell for reuse
what are cilia and undulipodia?
protrusions (bumps) from the cell
what are cilia and undulipodia surrounded by?
a cell surface membrane
what does each cilia and undulipodia contain?
microtubules ( components of cell skeleton which determine shape of cell)
what are cilia and undulipodia formed from?
centrioles (two bundles of microtubules at right angles to each other)
where in our body do we have hundreds of cilia ?
epithelial cells in our airways
why do we have hundreds of cilia in the epithelial cells of our airways?
to beat/ move the band of mucus
do nearly all cell types in the body have one cilium that acts as antenna?
yes
what does the cilium contain?
receptors
what do the receptors on the cilia allow the cell to do?
detect signals about its immediate environment
how many types of human cell have an undulipodia?
only one
what is an undulipodia?
a longer cilium
what is the name of the only human cell to have an undulipodia?
a spermatozoon
what does the undulipodia enable the spermatozoon to do?
move
