Cell structures Flashcards
Prokaryotes examples
bacterial cells
Eukaryotes examples
Animal, plant cells
prokaryotes vs eukaryotes
nucleus structure [4]
- nuclear envelope (double membraned, continuous w ER)
- nuclear pores
- DNA
- nucleolus (ribosomal subunits are synthesised)
Nucleus f(x) [GEC]
G- contain genetic information
E- essential for cell division
C- control cell activities
Cell surface membrane structure
- selectively permeable membrane
- Fluid mosaic model:
+ fluid: phospholipids are able to move freely and laterally along the phospholipid bilayer
+ mosaic: different proteins are randomly scattered and embedded among the phospholipids
Cell surface membrane f(x) [3]
- compartmentation and specialisation of cell
- selectively permeable membrane
- forms boundary that separates cell contents from the extracellular surrounding
Cytoplasm
- semi-fluid structure
- 90% water + 10% dissolved solutes
protoplasm
cytoplasm + cell surface membrane + nucleus
cytoplasm f(x) [2]
- main site for metabolic activities
- where chemical reactions occur
Ribosome structure [NEST]
N: non-membrane bound
E: exist as free ribosomes floating in the cytoplasm or attached to the rER
S: spherical in shape
T: 2 subunits(RNA + protein)
not organelle btw
ribosome f(x) [5]
- site of p.p. synthesis
- translate gene carried by mRNA into p.p., p.p. folds into specific 3D conformation of protein
free ribosomes:
- synthesise proteins that function WITHIN cytoplams
ribosomes that are att. to rER synthesise proteins that are:
- meant to be secreted out of the cell
- packaged within lysosomes
- be embedded into the membranes
Endomembrane system
- endoplasmic reticulum
- Golgi body
- vesicles and lysosomes
- outer membrane of nuclear membrane
Rough endoplasmic reticulum (rER) structure [4]
- continuous w nuclear envelope
- 3D network of interconnecting flattened membranes
- SINGLE membrane structure
- ribosomes are att. to ER membranes
rER f(x) [2]
- folding p.p. into proteins
- transport protein for secretion
- transport vesicles containing protein bud/pinch off from rER and are transported to the Golgi body for further chemical modification
sER structure [4]
- SINGLE MEMBRANE STRUCTURE
- 3D network of interconnecting tubular membrane
- no ribosomes att. to membrane surface
- could be continuous w rER or nuclear envelope
sER f(x) [2]
- synthesis of LIPIDS
- enzymes in sER synthesise lipids (eg. phospholipids and steriods[eg. cholesterol]) - detoxification
- converts harmful/toxic substances into more soluble and less harmful substances (easier for secretion)
Golgi body structure [3]
- several stacks of flattened membrane-bound bodies
- not continuous with nuclear envelope
- vesicles can be seen fusing w the cis face, pinching off frm the trans face
Golgi body f(x) [3]
- CHEMICAL MODIFICATION:
- modification of proteins that are transported from the rER and sER via transport vesicle
- contain enzymes to catalyse the addition/removal of sugars frm proteins, addition of sulfate groups and phosphate groups - SORTING AND PACKAGING:
- proteins/lipids that are SECRETED are sorted and packaged into SECRETORY VESICLES - FORMATION OF LYSOSOMES:
- specialised vesicles containing LYSOSOMAL ENZYMES bud off frm the Golgi body
- remains in cytoplasm
types of vesicles
- transport vesicles
- secretory vesicles
- lysosomes
- vacuoles
PROTEIN SYNTHESIS in cells (8 steps)
Vesicles and lysosomes structure [3]
- tiny sacs bound by a single membrane
- formed when some membrane buds off to ENCLOSE A SUBSTANCE
- formed frm sER, rER and Golgi body
vesicle f(x) [1]
vesicle f(x)
lysosome f(x)
lysosome structure
types of endocytosis [3]
- pinocytosis
- phagocytosis
- receptor-mediated endocytosis
Mitochondrion structure [4]
- cylindrical shaped
- double membrane:
= outer membrane is smooth
= inner membrane has numerous folds (CRISTAE) - membranes separated by intermembrane space
- matrix is compartment enclosed by the inner mitochondrion membrane
f(x) of cristae
to increase surface area to ratio, provides a larger surface area for chemical reactions
Mitochondrion f(x)
site of respiration
Chloroplast structure [5]
Chloroplast f(x)
Vacuole structure [2]
- single membrane (tonoplast in plants)
- contain cell sap
in animal cells: they are small but numerous (temporary)
Vacuole structure [2]
- single membrane (tonoplast in plants)
- contain cell sap
in animal cells: they are small but numerous (temporary)
vacuole f(x) [3]
- helps develop turgidy
- storage of starch, pigments and defensive compounds
- deposition site
Cell wall structure [4]
cell wall f(x) [3]
Root hair cell structure [4]
Root hair cell f(x)
Xylem structure
xylem f(x)
red blood cell structure [4]
red blood cell f(x)
