3.4 Eukaryotic cell structure Flashcards
What does a nucleus contain?
The organism’s hereditary material and controls cell’s activities
About 10-20 μm diameter
What parts does the nucleus have? (5 parts)
The nuclear envelope, nuclear pores, nucleoplasm, chromosomes (linear DNA, protein bound) one or more nucleolus (manufactures rRNA and assembles ribosomes)
Functions of the nucleus?
To act as the control centre of the cell through production of mRNA and tRNA and hence protein synthesis
Retain genetic material in the form of DNA and chromosomes
Manufacture ribosomal RNA and ribosomes
What shape is a mitochondria?
Rod shaped
1-10 μm in length
Structure of mitochondrion?
Double membrane (control entry and exit of material) Folding of membranes form Cristae
Cristae Extension of the inner membrane, increase surface area for attachment of enzymes and other proteins in respiration
Matrix contains proteins, lipids, ribosomes and DNA
Functions of the mitochondria?
Site of aerobic respiration, responsible for producing energy-carrier ATP
Give examples of metabolically active cells
Muscle and epithelial cell
Epithelial cells require lots of ATP to absorb substances from the intestine via active transport
Give structure of the chloroplast
Chloroplast envelope (double plasma membrane, highly selective)
Grana with (thylakoid stacks) that has photosynthetic pigment (chlorophyll),
Stroma (a fluid filled matrix where sugar synthesis takes place, can also have starch grains
What is the function of a chloroplast?
Carry out photosynthesis
How are chloroplasts adapted to their functions (harvesting sunlight and carrying out photosynthesis)?
Granal membranes provide large surface area for attachment of chlorophyll and enzymes for 1st PS
Fluid in stroma possess all enzymes needed for 2nd PS
Chloroplasts contain (both DNA and ribosomes) so they can easily manufacture some (proteins) needed for photosynthesis
What connects thylakoids?
Lamellae
What do chloroplasts produce from CO2 and H20?
Carbohydrates
What types of endoplasmic reticulum are there?
Rough ER
Smooth ER
How do you differentiate rough ER and smooth ER?
Rough has ribosomes on the outer surface of the membranes;
Smooth does not and look more tubular
Function of rough ER?
Provides large surface area for synthesis of proteins and glycoproteins
Provides pathway for the transport of materials, especially proteins (made in ribosome)
What is a glycoprotein?
A protein that has a carbohydrate attached to it
What is the function of smooth ER?
Synthesise, store and transport lipids
Synthesise, store and transport carbohydrates
what kind of cells have a very extensive ER?
Those that manufacture and produce lots of (carbohydrates, proteins and lipids)
Where does the ER tend to connect to?
Nuclear membrane
Structure of the Golgi apparatus?
3 points
Contains a stack of membranes that make up cistern (flattened sacs)
with rounded hollow vesicles (floating on sides?)
Golgi vesicles regularly pinched off at Golgi cisternae
Vesicles then move to CSM and release insides
Functions of the Golgi apparatus?
Add carbohydrates to proteins to form glycoproteins
Produce secretory enzymes (proteins), e.g those form pancreas
Secrete carbohydrates, e.g ones used for making cell walls in plants
Transport, modify and store lipids
Form lysosomes (hydrolytic enzymes)
When are lysosomes produced?
When vesicles produced by the Golgi apparatus contains enzymes such as protease and lipase
What enzyme do lysosomes contain?
Lysozyme
What does lysozyme do?
Hydrolyse the cell walls of certain bacteria
What are the functions of a lysosome?
Hydrolyse material ingested by phagocytic cells, e.g WBC and bacteria
Release enzymes to the outside of cells (exocytosis) to destroy material around cells
Digest worn out organelles so useful chemicals can be reused
Completely break down cells after they have dies (autolysis)
Where are lysosomes most found?
In secretory cells, such as epithelial cells and phagocytic cells
What do ribosomes do?
Synthesise proteins
What types of ribosomes are there?
80S (eukaryotic)
70S (prokaryotic)
where can ribosomes be found?
Attached onto the rough ER or floating freely in the cytoplasm
Why are cell walls so strong?
Have cellulose microfibrils
Structure of a cell wall?
Consist of a number of polysaccharides, e.g cellulose
Has a middle lamella to mark boundaries between cells
Function of cell wall?
Provide mechanical strength to prevent cell bursting due to osmotic entry of water
Allow water to pass through
What do fungi cell walls contain instead of cellulose?
Chitin
What are algae cell walls made of?
Cellulose or glycoproteins or both
What is the structure of a vacuole?
To contain mineral salts, sugars, amino acids, wastes and sometimes pigements such as anthocyanin
What is the function of a vacuole?
Support herbaceous plants
The sugar and amino acids can act as a temporary food store
Pigments can colour petals and attract pollinating insects
What is the name of the single membrane around a vacuole?
Tonoplast
