Eukaryotic cell Flashcards
Define a cell
the basic unit of life
organelles
small structures inside a cell with specific function
structure of cell membrane
2 layers of phosholipids, proteins
function of cell membrane
what comes in and what goes out of cell
- thats why it is semi permeable
structure of cytoplasm
made of a fluid (cytosol) and organelles except for nucleus)
function of cytoplasm
all of the cells contents lie between the cell membrane and the nucleus
structure of nucleus
membrane bound that contains DNA
function of nucleus
‘control centre’ that regulates DNA & RNA actions
structure and function of nucleus envelope
f- regulates what enters and exits the nucleus
s- double layer of lipids
structure and function of nucleolus
f- produces RNA, which makes proteins
s- inside Nucleus, separate from DNA
Function of DNA
f- info on how to make proteins
a. chromatin (unorganised DA)
b. chromosomes (organised DNA (present before cell division)
structure of DNA
made of nucleotides, locked in the nucles
structure of Endoplasmic reticulum
tubes and channels
function of ER
transport for proteins
RER- has ribosomes
SER - no ribosomes
Function of ribosomes
Make proteins
Structure of ribosomes
Small circular organelles
Structure of vacuoles & vesicles
Small membrane bound organelle
Function of vacuole and vesicles
Storage for water, nutrients and waste
Structure and function of lysosomes
F - packet of enzymes that break materials down in a cell
S - small membrane bound organelle
Function of mitochondria
To produce energy for the cell, site of cellular respiration “the powerhouse”
Structure of mitochondria
Double membrane bound, kidney shaped
Function of golgi apparatus
Packages, labels and ships proteins out of cell
Structure of Golgi apparatus
Pancake shaped, layered organelle
Structure of cytoskeleton
Provide support and structure for the cell
Structure of cytoskeleton
Tubules
Structure of centrioles
Tubules
Function of centrioles
Micro tubules that help divide the cell in cell division
Rough ER
- covered in ribosomes
- sheet like in appearance
- prominent in cells carrying out extensive protein synthesis
Smooth ER
- prominent in cells with lipid and drug metabolism
- is more tubular
Main functions of ER
- Detoxification of drugs
- Translocation of proteins
- Glycosylaytion of proteins
- Assembly of lipid bilayers
F of lysosomes
- stomach of cell (digests macromolecules)
- clean up crew of cell (cleans up broken organelles)
Lysosomal enzymes
- work best at ph5 (so organelle creates custom pH)
- does this by pumping H+ ions from cytosol into lysosomes
Apoptosis
- auto-destruct process
- lysosomes break open and kill cell
Golgi body also known as
- golgi complex
- Golgi apparatus
- Dictyosome (plants )
S of golgi body
- stack of 4-6 flattened smooth membrane bounded compartments with associated vesicles
- slightly concave, polarized structure
F of Golgi body
- Protein modifications
- addition of other molecules/groups to the protein to change its shape and function - Protein processing
- cleavage of peptides to produce activated proteins
3 . Protein sorting and localisation
Protein modifications
- addition of sugars (glycosylation to give proteoglycans)
- of fatty acids (productions of lipoproteins)
- of phosphate groups (phosphorylation)
Function of proteoglycans
- they are are major component of the extracellular matrix, the ‘filler’ substance existing between cells in an organism
- bind cations e.g sodium and water through the matrix
- individual functions of proteoglycans are due to their protein core
Protein processing
- many polypeptides, hormones and neurotransmitters are synthesised as inactive precursor molecules
- the active form is liberated by proteolysis
Protein sorting
- mammal approx 10,000 diff kinds of proteins
- for a cell to work properly each one of these proteins must be localised to the correct membrane or compartment
- DNA - modifying enzymes such as RNA and DNA polymerases are made on CYTOSOLIC ribosomes and then transported to the NUCLEUS
- ion-channel, transporter and receptor proteins need to be localised in the plasma membrane
- the process of directing each polypeptide to a particular destination - depends on the presence of sorting SIGNALS and multiple SORTING EVENTS
Protein sorting (golgi apparatus)
A. Lysosomal pathway
B. Constitutive pathway
C regulated secretion
Mitochondria
- in all eukaryotic cells
- fairly large 1um diameter
- have double membrane structure (envelope)
- major function ATP generation
- the mitochondria converts food energy e.g carbohydrates to fatty acids
Mitochondrial function (Oxidative metabolism)
- Large molecules broken down into smaller subunits
- Numerous small molecules are converted into a few key molecules which plays a central role in metabolism
- Oxidation to produce ATP
ATP
- molecular unit of intracellular energy currency
- total quantity of ATP in adult is approx 0.10mol/L
- but approx 100-149 mol/L of ATP is required daily, so we only have enough for 2 minutes
- so each ATP molecule is recycled 1000 to 1500 times a day
Mitochondrial ATP synthesis
- The energy from the high energy electrons is used to pump protons (H+) across the inner mitochondrial membrane from the matrix and into the inter-membrane space
- the protons then flow back down the gradient and this energy drives coupled ATP synthesis
Cytoskeleton
- Provides supporting framework for the cell and gives the cell its particular shape
- Actin filaments anchored just underneath the plasma membrane are responsible for changing the shape of the cell
Cytoskeleton and its associated motor proteins organises and moves the cytoplasmic contents
- movement of organelles (microtubules)
- movement of vesicles (micro tubules)
- the whole cell movement is polarised and directional
- movement of cells is important in development processes
Components of cytoskeleton
- Microtubules
- made of tubulin
- 25nm diameter
- e.g mitosis, ciliia, flagella, centrioles - Actin filaments (microfilaments)
- made of actin
- 6nm diameter
- e.g cytoplasmic streaming - Intermediate filaments
- several proteins such as keratin
- intermediate size, i.e 10-15nm diameter
- e.g keratins in skin, hair,nails (animal horn) etc
