Flashcards in 220.127.116.11 Organelle Structure and Function Deck (39):
What is the nuclear membrane?
Double membrane that controls entry/exit of materials to and from the nucleus.
What are nuclear pores?
Holes in the nuclear membrane that allow mRNA and ribosomes to exit.
What is the nucleoplasm?
Jelly-like material that makes up the bulk of a nucleus.
What is the nucleolus?
Small spherical region in a nucleus that contains ribosomal RNA (rRNA) and manufactures ribosomes.
What is chromatin?
An uncondensed complex of DNA and protein.
What does chromatin condense into prior to cell division?
What is the function of a mitochondrion?
The site of cellular respiration.
In which eukaryotic cell would you not find a nucleus and why?
Red blood cells
To give more room to carry oxygen
Which cells contain many mitochondria?
Metabolically active cells such as:
Intestinal epithelial cells
How are mitochondria adapted to carry out their function?
1. Cristae - extensions of inner membrane provide large surface area for respiration reactions to take place.
2. Matrix - inner space contains ribosomes, and DNA so that respiratory enzymes can be quickly produced when needed.
What is the function of a chloroplast?
To carry out photosynthesis
Carbon dioxide + Water --> Glucose + Oxygen.
Which plant cells do not contain chloroplasts and why?
Root hair cells - no sunlight underground.
What is the chloroplast envelope?
A partially permeable double membrane that surrounds a chloroplast.
What are thylakoids?
Flattened sacs found within a chloroplast that contain chlorophyll.
What is chlorophyll?
The green pigment found inside the thylakoids of chloroplasts that captures light energy.
What are grana?
Stacks of thylakoids.
The place where the 1st stage of photosynthesis takes place (light absorption).
What is the stroma of a chloroplast?
The fluid filled space within a chloroplast.
Where the 2nd stage of photosynthesis takes place (sugar synthesis).
How are chloroplasts adapted to carry out their function?
1. Granal membranes provide a large surface area for photosynthesis reactions to take place.
2. Stroma contains enzymes for 2nd step of photosynthesis to take place (sugar synthesis).
3. Contain DNA and ribosomes so can quickly produce enzymes required for photosynthesis when needed.
What is meant by lamellae?
The flattened sacs and hollow tubes of endoplasmic reticulum and golgi apparatus are called...
The rough and smooth endoplasmic reticulum, Golgi apparatus and secretory vesicles are all part of the...
endomembrane system (i.e. protein transport out of cell)
Why is the rough endoplasmic reticulum described as rough?
It is 'studded' with ribosomes.
How does the structure of the rough endoplasmic reticulum relate to its function?
1. Folds provide a large surface area for protein synthesis.
2. Cisternae provide a pathway for transport of proteins.
3. Can form vesicles to allow proteins to exit.
What happens at the 'cis face' of the Golgi apparatus?
Incoming vesicles containing proteins, lipids and carbohydrates are received.
What happens at the 'trans face' of the Golgi apparatus?
Modified/labelled proteins, lipids or carbohydrates are TRANSferred out of the Golgi apparatus in secretory vesicles.
What is the function of the Golgi apparatus?
1. Adds carbohydrates to proteins to form glycoproteins.
2. Forms lysosomes.
3. Transports and modifies stored lipids.
4. Produces secretory enzymes e.g. in pancreatic or epithelial cells.
5. Secretes carbohydrates for cell walls.
Describe the process of lysosome action on an engulfed bacterium.
1. Hydrolytic enzyme enters cis face of Golgi apparatus.
2. Lysosome containing hydrolytic enzyme (lysozyme) exits trans face of Golgi apparatus.
3. Lysosome merges with vesicle containing engulfed bacterium and digests bacterium.
4. Soluble debris absorbed into cell. Insoluble debris is egested from cell.
What is the function of the smooth endoplasmic reticulum?
1. Synthesise, store and transportation of lipids.
2. Synthesise, store and transportation of carbohydrates.
3. Detoxification of harmful substances.
What is the function of a cell wall?
1. Prevents a plant cell bursting due to osmosis.
2. Give plant cells mechanical strength.
3. Structure allows water to pass through it via osmosis.
What is the function of a vacuole?
1. Makes plant cells turgid (firm)
2. Contains sugars/amino acids which act as a temporary food store.
3. Contains coloured pigments which attract pollinating insects e.g. petals.
Where are 80S ribosomes found?
Where are 70S ribosomes found?
Which are bigger: 70S or 80S ribosomes?
80S (25nm as opposed to 20nm 70S)
Ribosomes are made from 2 parts. What are these parts called?
name 2 molecules found in a ribosome
RNA and protein
What process do you use isolate an organelles from a cell?
What does cell fractionation involve?
1. break open cells and remove debris
2. add cold isotonic buffer
3. spin in centrifuge - heaviest organelle pellets 1st
In cell fractionation which pellet would you find the chloroplasts?