Cell Structure Flashcards
(22 cards)
Cell-Surface Membrane
boundary between cell cytoplasm and environment
controls movement of substances in and out of cell, allows different conditions to be established inside and outside a cell
Nucleus
contains genetic material
Nuclear Envelope
**Double membrane that surrounds nucleus.
**controls entry and exit of materials **in and out the nucleus + contains the reactions taking place within it
Nuclear pores
allow passage of large molecules (eg mRNA) out the nucleus
Nucleoplasm
Granular,jelly like material that makes the bulk of the nucleus
Chromosomes
Consists of protein bound, linear DNA
Nucleolus
Small spherical region within the nucleoplasm
It manufactures ribosomal RNA and assembles the ribosomes
There may be more then one nucleolus in a nucleus.
Mitochondrion
Site of the aerobic stages of respiration and therefore responsible for the production of ATP
Metabolically active cells (eg, muscle and liver cells) have more mitochondria
Double membrane
Controls the entry and exit of materials
Inner membrane
folded to form extensions called cristae
These provide a large surface area for the attachment of enzymes involved in respiration
Matrix
Contains the proteins, lipids, ribosomes and DNA that allows the mitochondria to control the production of some of their own proteins
Endoplasmic reticulum
system of sheet-like membranes, which is continuous with the outer nuclear membrane and is sprad throughout the cytoplasm of the cells
The membranes enclose a network of tubules and flattened sacs called cisternae
Rough Endoplasmic reticulum (RER) - ribosomes on surface of membrane
-** larger SA **for the synthesis of proteins
- folds polypeptides to secondary and tertiary structures
- proteins are then packaged into vesicles to be transported into the Golgi apparatus
Smooth Endoplasmic Recticulum (SER)
- lacks ribosomes on its surface and is more tubular in appearance
Synthesises, stores and transports lipids and carbohydrates
Golgi apparatus
Consists of a stack of membranes that make up flattened sacs or **cisternea. **
recieves vesicles from RER and the SER
- processes and packages new proteins and lipids
- proteins can be modified by adding non-protein components, such as carbohydrates to them
- the modified proteins and lipids are then packaged into the Golgi vesicles, which then transport proteins and lipids to their required destination
- Lysosomes are formed by the Golgi apparatus
Lysosomes
Vesicles filled with enzymes such as protease, lipases and lysozymes (enzymes that hydrolise the cell walls of certain bacteria). The lysosomes isolate these enzymes from the rest of the cell preventing cell damage.
Roles
- hydrolysing material ingested by pathogenic cells
- releasing enzymes outside of cells (exocytosis)
-digesting old and worn out organelles
- breaking down cells after they have died (autolysis)
Ribosomes
Site of protein
The have two subunits - one large, each contain ribosomal RNA and protein.
They may occur in the cytoplasm or be associated with the RER.
They are small but occur in vast numbers.
There are two types.
- 80s - found in eukaryotic cells
-70s - found in prokaryotic cells, mitochondria and chloroplasts, is slightly smaller.
Cytoskeleton
This is made up of protein fibres that run throughout the cell.
The role of the cytoskeleton is is to control cell movement and movement of organelles within the cell, and to also provide mechanical strength to the cell.
Chloroplasts (in plants and algae)
Site of photosynthesis
Chloroplast envelope
Double plasma membrane that controls what enters and leaves the chloroplast.
Grana (plural)
Where the first stage of photosynthesis (light absorption) takes place.
They contain stacks of disc-like structures called thylakoids that contain chlorophyll. The thylakoid membranes provide a large SA
