cell structure eukaryotic Flashcards
plasma cell surface membrane
regulates the movement of substances into and out of the cell. has receptor molecules on it which allow it to respond to chemicals (e.g. hormones)
cell wall
- rigid structure that surrounds plant cells and supports them
- made up of cellulose (carbohydrate)
what is the nucleus made up of and what does it do
controls the cell’s activities
- nuclear envelope
- nucleolus
- nuclear pores
- chromatin (made from DNA and proteins)
nucleolus
- makes ribosomes
- composed of proteins and RNA
- RNA is produced to rRNA which combines with proteins to form ribosomes
nuclear envelope
- double membrane
- protects DNA inside from damage in the cytoplasm
nuclear pores
- allow molecules to move into and out of the nucleus
- DNA is too large to leave so it is transcribed to RNA molecules which can leave via nuclear pores
lysosome
- specialised forms of vesicles
- contains digestive enzymes
- these are kept separate from cytoplasm by the membrane
- they are used to digest invading cells, to break down worn out cell components
ribosome
- made up of proteins and RNA
- not surrounded by a membrane
- site of protein synthesis
rough endoplasmic reticulum
- system of membranes enclosing a fluid-filled space
- surface covered in ribosomes
- folds and processes proteins that have been made at ribosomes
smooth endoplasmic reticulum
- system of membranes enclosing a fluid-filled space
- synthesises and processes lipids and carbohydrates
vesicle
- fluid-filled sac in the cytoplasm, surrounded by a membrane
- transports substances into and out of a cell and between organelles
- some are formed by the golgi apparatus or endoplasmic reticulum, or cell surface
golgi apparatus
- group of fluid-filled, membrane-bound, flattened sacs.
- vesicles are often at the edges of the sacs
- processes and packages new lipids and proteins
- makes lysosomes
mitochondria
-double membrane
- outer membrane
- inner membrane folds into cristae structures
- fluid interior is called the matrix
- site of aerobic respiration where ATP is produced
- large numbers found in active cells that require a lot of energy
chloroplast
- flattened structure found in plant cells
- double membrane
- contains thylakoid membranes inside which are stacked up to form grana (contain chlorophyll)
- grana are linked by lamelle (thin, flat pieces of thylakoid membrane)
- stroma is the thick fluid found in the cell
- site of photosynthesis
- photosynthesis happens in grana and stroma
centriole
- small, hollow cylinders made of microtubules
- animal cells, only some plant cells
- involved with the separation of chromosomes during cell division
- 2 associated centrioles form a centrosome
- centrosome is involved in assembly and organisation of spindle fibres during cell division
cilia
-small, hair-like structures on the surface membrane of some animal cells
- in cross section, they have an outer membrane and a ring of 9 pairs of microtubules, with 2 microtubules in the middle
- microtubules allow the cilia to move
- this moves substances along the cell surface
flagellum
- on eukaryotic, they are like cilia but longer
- stick out from the cell surface
- 2 microtubules in the centre and 9 pairs around the edge
- microtubules contract to make flagellum move
- flagella are used like outboard motors to propel cells forward
vacuoles
- membrane bound (tonoplast) sacs in the cytoplasm containing cell sap
- tonoplast is selectively permeable
- large permanent vacuoles are important in the maintenance of turgor
cytoskeleton
- in the cytoplasm of eukaryotic cells
- network of fibres necessary for the shape and stability of the cell
- organelles are held in place by it and their movement is controlled by it
its 3 components are
- microfilaments
- microtubules
- intermediate fibres
microfilaments
- protein actin
- contractible fibres
- responsible for cell movement and cell contraction during cytokinesis
microtubules
- globular tubulin proteins polymerise to form tubes
- form a scaffold-like structure which determines cell shape
- act as tracks for movement of organelles around the cell
- make up spindle fibres (segregation of chromosomes in cell division)
intermediate fibres
- give mechanical strength to cells
- help maintain cell integrity
