cells and microscopes Flashcards
what are the components of the cytoskeleton
- microfillaments
- microtubules
- intermediate fibres
what are microfillaments
- made from protein called actin
- responsible for cell movment and cell contraction during cytokinesis
what are mictrotubules
- made from a globular protein called tubulin
- polymerise to form tubes
- act as tracks for movement of organelles
what are intermediate fibres
- give mechanical strength to cells
- help maintain their integrity
what is the structure of the nucleus
- nuclear envelope: double membrane which compartmentalises the nucleus and prevents damage
- Nuclear pores: allows molecules to enter and leave
- chromatin : contains genetic code
- nucleolus: makes ribosomes composed of RNA
what is the function of the nucleus
1) Controls all the activity of the cell.
2) Where the Genetic Code (DNA) of the cell is stored, replicated,
and copied into RNA (transcribed).
3) The Nucleus is attached to the Rough ER so the mRNA can easily
get to ribosomes
what is the structure of the rough endoplasmic reticulum
System of hollow tubes and membrane bound sacs which form sheets called cisternae. attached to the nucleus and covered with ribosomes. • Consists of an interconnected system of flattened sacs.
what is the function of the rough endoplasmic reticulum
Site of protein synthesis
what is the function of the smooth endoplasmic reticulum
similar to RER but lacks ribosomes -is a system of
interconnected tubules.
SER: responsible for carbohydrate & lipid synthesis, and storage.
what is the structure of ribosomes
A 2 subunit organelle.
• Made from RNA and protein.
• Not membrane bound.
• Very small organelles: about 22nm in diameter.
• Found free floating in the cytoplasm or attached
to the Rough ER
what is the fucntion of ribosomes
These are where protein is made.
• They assemble amino acids into proteins in chains using mRNA.
what is the structure of mitochondria
Oval shaped.
• Surrounded by two membranes (double membrane).
• The inner membrane forms finger-like structure
called cristae which increases the surface area.
• The solution inside is called a matrix which contains
enzymes for respiration.
• Mitochondrial DNA – Small amounts of DNA, enable
mitochondrion to reproduce and create enzymes.
what is the function of mitochondria
Site of aerobic respiration.
• As a result of respiration, they produce ATP (energy
carrier in cells).
what is the structure of golgi body
Stack of flattened, membrane bound sacs
(cisternae).
These are continuously formed from the ER at one
end and budding off as Golgi vesicles at the other
what is the function of the golgi body
• Allows internal transport.
• Receives proteins from the RER
• Modifies and processes molecules (such as new lipids
and proteins) and packages them into vesicles.
• These may be secretory vesicles (if the proteins need
to leave the cell) or lysosomes (which stay in the cell).
• Makes lysosomes
• Lipid synthesis
what are lysosomes
They are spherical sacs surrounded by a single membrane. • They contain powerful hydrolytic digestive enzymes known as lysozymes. • Their role is to break down worn out components of the cell or digest invading cells.
what is the structure of the centrioles
A component of the cytoskeleton, composed of many microtubules. • Small hollow cylinders that occur in pairs next to the nucleus in animal cells only. • Each centriole contains a ring of 9 microtubules.
what is the function of centrioles
Makes a copy of itself during cell division
and then helps to form the spindle in
cell division.
what is the structure of cilia
• ‘Hair like’ extensions that protrude from some
animal cell types.
• In cross section they have an outer membrane
and a ring of nine pairs of protein
microtubules inside with two microtubules in
the middle.
• Known as a 9 +2 arrangement.
• Arrangement allows movement.
what is the function of cilia
sensory function (e.g. nose), beat
creating a current to move
fluid/mucous/objects
For locomotion
what is the structure of flagella
Similar to flagella but longer.
• They stick out from the cell surface and are
surrounded by the plasma membrane.
• Like cilia they have a 9 +2 arrangement.
• Function:
• (Whip-like) enables a cells mobility.
• The microtubules contract to make the flagellum
move.
• Propel cells forward e.g. sperm cells
what is the structure and function of chloroplasts
• Double membrane which encloses the stroma. • Stroma contains: Starch grains, lipid stores, DNA, RNA, ribosomes. • Series of membrane-bound flattened sacs called thylakoids in the stroma. Thylakoids stacked together are called grana. • Grana are linked together by lamellae. • The grana contain chlorophyll Function • Photosynthetic reactions
what are plasma membranes
Structure
• The membrane found on the surface of animal cells and inside the
cell wall of plant and prokaryotic cells.
• A phospholipid bilayer.
• Composed of proteins and lipds.
Function
• Regulates the movement of substances into and out of the cell.
• Contains receptor molecules which allow it to respond to
chemical like hormones
what is the function and structure of cell wall
Structure:
• Made of cellulose microfibrils– complex carbohydrate
• Cell wall is fully permeable to substances
• Thin layer called the middle lamella which marks the
boundary between adjacent cell walls and ‘cements’
adjacent cells together.
Function:
• Gives the plant mechanical strength
• Gives the plant cell support and it’s shape
• Contents of plant cell can ‘push’ against the cell wall
(turgid cell). This gives the cell (and the whole plant)
good support.
explain how the process of protein production
1.) proteins are synthesisied on the ribosomes bound ot the RER
2.) then they pass into its cisternae and are packaged into transport vesicles
3.) vesiciles move towards to the golgi body via cytoskeleton
4.) the vesicles fuse with the cis face of the golgi body and proteins enter
5.) these proteins are structurally modified before leavin the golgi body
the vesicles fuse with the cell surface membrane releasing their contents by exocytosis.
what are the 2 types of electron microscopes
- transmission electron mictroscope
- scanning electron microscope
describe the snanning microscope
- a beam of electrons is sent across the surface of a specimen
- and the refelcted electrons are collected
- resolving power is 3-10n,
- 3 dimensional images are produced (3D)
describe the transmission microscope
- a beam of electrons is transmitted through a specimen an focused to produe an image
- best resolution of 0.5nm
define resolution
- Resolution is how well a microscope distinguishes between two points that are close together.
define magnification
- how many times larger the image is than the actual size of the object being viewed
