cell structure Flashcards
Which organelles are in a plant cell but not in an animal cell?
Cell wall
vacuole (permanent with cell sap)
chloroplast
Describe the plasma membrane.
it is the membrane on the surface of animal cell but inside the cell wall of plant and prokaryotic cells
What is the function of the plasma membrane?
- It regulates the movement of substances in and out of the cell
- has receptor molecules which allow it to respond to chemicals such as hormones
Describe the cell wall
- a rigid structure that surrounds plant cells
- it is mainly made of cellulose (carbohydrate) or chitin (also carbohydrate)
What is the function of the cell wall?
supports plant cells
Describe lysosomes
- round organelle surrounded by a membrane with no clear internal structure
- contains digestive enzymes
- membrane separates organelle content from cytoplasm
What is the function of lysosomes?
digests invading cells or breaks down work out cell components
Describe ribosomes
small organelle that floats freely in the cytoplasm or is attached to the RER
What is the function of ribosomes?
site of protein synthesis
Describe the SER
sheet like membranes enclosing a fluid filled space throughout the cell
What is the function of the SER?
synthesis and processes lipids
Describe the RER
- sheet like membranes enclosing fluid filled space throughout the cell
- surface covered with ribosomes
What is the function of the RER?
folds and processes proteins made at the ribosomes
Describe the nucleus
- large organelle surrounded by nuclear envelope
- nucleus contains nucleolus and chromatin
What is the function of the nucleus?
- controls genetic material
- controls cell activity
Describe chromatin
made up of proteins and DNA
What is the function of chromatin?
controls cell activity
What is the function of nuclear pores?
allow large molecules like mRNA to exit the nucleus
Describe the nuclear envelope
a double membrane surrounding the nucleus with pores
What is the function of the nuclear envelope?
controls the entry and exit of materials from the nucleus
What is the function of the nucleolus?
synthesis ribosomes
Describe vesicles
small fluid-filled sacs in the cytoplasm surrounded by a membrane
What is the function of vesicles?
transports materials in and out of the cell via cell surface membrane where fusion happens.
- During fusion contents are released out of the membrane by exocytosis
- when contents are taken in from the membrane, it is called endocytosis
Describe the Golgi Apparatus
an organelle that contains membrane-bound, flattened sacs with surrounding vesicles
What is the function of the Golgi Apparatus?
processes, modifies and packages proteins and lipids into vesicles
- also makes lysosomes
Describe the mitochondria
oval shaped organelle with a double membrane
What is the function of the mitochondria?
- involved in aerobic respiration
- responsible for the production of ATP molecules which carry energy
- outer membrane controls the flow of materials in and out of the mitochondria
Describe the cristae
extensions of the inner membrane in mitochondria
What is the function of cristae?
increase the surface area for the attachment of enzymes
Describe the matrix
fluid filled space in the middle of the mitochondria
- contains lipids, trace DNA and enzymes for respiration
Describe centrioles
- small, hollow cylinders of microtubules
- in all animal cells and some plant cells
What is the function of centrioles?
involved in the separation of chromosomes during cell division
Describe the cilia
small, hair-like structures on the plasma membrane of some animal cells
Describe the chloroplast
- small, flattened structure with stacks of membranes (thylakoid membranes)
- surrounded by double membrane
What is the function of chloroplast?
- site of photosynthesis
- some parts happen in grana (stacks of thylakoid membranes)
- some parts happen in the stroma (thick fluid found in chloroplasts)
What are the 4 functions of cytoskeleton?
- microtubules and microfilaments support the cells organelles keeping them in their positions
- helps strengthen the cell and maintain its shape
- responsible for the transport of organelles and materials within the cell
- proteins in a cytoskeleton also cause the cell to move e.g. propel forward
Describe a microtubule
a tiny protein cylinder
Describe a microfilament
a very thin protein strand
Describe prokaryotes
single-celled organisms with no nucleus or few/no membrane bound organelles
Describe eukaryotes
they have cells with a nucleus and many membrane bound organelles
What are the features of a prokaryote
- extremely small in size
- circular DNA
- no nucleus
- few/no membrane bound organelles
- cell wall of a polysaccharide
- 70s ribosomes
- flagella of flagellin
What are the features of an eukaryote
- large cells
- linear DNA
- nucleus present
- many membrane bound organelles
- cellulose cell wall in plants and chitin cell wall in fungi
- 80s ribosomes
- flagella of microtubules
Briefly explain protein synthesis
- mRNA leaves nucleus and either travels to the ribosomes attached to RER or floats freely in cytoplasm
- ribosomes on RER produce proteins which are folded processed and packaged into vesicles to the Golgi
- Golgi modifies the proteins which are then packaged in vesicles
- vesicles fuse with the plasma membrane via exocytosis to release contents outside cell or are inserted into the membrane
