3.2 Cells 3.2.1.1 Structure Of Eukaryotic Cells Flashcards
What type of organelles do eukaryotic cells all contain
Membrane bound organelles
What does the nucleus act as and how
E.g
The control centre of the cell by producing components needed for protein synthesis
E.g mRNA, tRNA, ribosomes
What does the nucleus contain and in what form
Genetic material in chromosomes
5 parts of a nucleus
Nuclear envelope Nuclear pore Nucleolus Nucleoplasm Chromatin
What’s the membrane of the nuclear envelope like
Double membrane, phospholipid bilayer
2 things the nuclear envelope does in a cell
Controls movement of substances in + out of nucleus
Helps maintain shape of nucleus
What does nuclear pore allow
Allows some molecules (e.g RNA) to move between nucleus + cytoplasm
What’s the most dense organelle in the nucleus
Nucleolus
What 2 things does the nucleolus do
Synthesises sub-unit components of ribosomes
Makes rRNA
When do chromosomes form
When the cell is dividing
What’s the nucleoplasm
Granular, jelly-like substance
What’s chromatin
What does it do
DNA wrapped/coiled around histones (proteins)
Controls cells activities
What are ribosomes the site of
Protein synthesis
Where are ribosomes found
Freely in cytoplasm
Bound to the membrane of the Endoplasmic Reticulum
Where are ribosomes formed
What are they made up of
Formed in the nucleus
Made up of RNA and proteins
Where would u find large (80s) ribosomes
In plant/animal cells
What 3 places would u find small (70s) ribosomes
In bacterial cells, mitochondria + chloroplasts
How do the ribosomes form proteins
Between the small subunit and large subunit when they combine, in a gap
What’s the endoplasmic reticulum
Folded up membrane system/network
What part of the endoplasmic reticulum are ribosomes
Rough (RER)
Where does the protein transport and modifying process begin in a cell
The nucleolus
What’s the RER attached to
The nucleus’ nuclear envelope
What does the endoplasmic reticulum have that increases the rate of protein synthesis
A large surface area
Where do the synthesised proteins by the ER go to next
They pass into the lumen of the ER via pores and then travel to the Golgi apparatus in vesicles
When do the proteins become modified
When they are in the Golgi apparatus
How do proteins edit the cell from the Golgi
They leave the Golgi in vesicles and then exocytosis occurs
What are vesicles
‘Empty’ protein sacs (filled with proteins)
What are the 2 types of membrane in the ER
Smooth ER
Rough ER
What does the smooth ER do
Synthesises, stores + transports lipids/carbs
What ER is covered in ribosomes
Rough ER
What’s cell’s is the endoplasmic reticulum common in
E.g
Cells that make/store lots of carbs, protein/lipids
E.g liver cells, epithelial cells in small intestine
How do proteins travel to the Golgi apparatus
In vesicles
What’s the Golgi apparatus made up of
How is this beneficial
Cisternae - flattened sacs of membrane
Gives a larger SA
What does the Golgi apparatus do (3)
Modifies proteins + lipids e.g lysosomes
Adds carbohydrates to proteins (glycoproteins)
Releases modified proteins in vesicles (bulk transport)
What does the Golgi apparatus produce when it adds carbohydrates to proteins
Eg
Glycoproteins e.g antigens
What are lysosomes a form of
Modified protein released from the Golgi apparatus
Lysosomes have a membrane, but what do they not have
Have no specified internal structure
What do lysosomes contain
E.g of a cell that contains many
Up to 50 digestive enzymes that break down waste in a cell
E.g white blood cells contain lysosomes
4 jobs lysosomes do
Digest harmful materials ingested by WBCs
Release enzymes outside the cell for digestion
Digest worn out organelles + recycle their chemicals
Break down cells that have died
What’s the membrane of a lysosome like
Thick, double membrane
What are the membranes like in a mitochondria
(Bilayer) surrounded by 2 membranes
What’s the inner membrane of mitochondria folded into
Cristae
What does the matrix in mitochondria contain
Enzymes involved in aerobic respiration
What’s the cytoplasm called in mitochondria
Matrix
What do mitochondria synthesise
ATP (produce energy)
What cells are mitochondria common in
E.g
Cells that need a lot of energy e.g muscle cells + epithelial cells
How can mitochondria make its own proteins + replicate alone
As it contains DNA + ribosomes
What on the cristae in mitochondria contains the ATP producing enzymes (ATP-ase) for respiration
Oxysomes
What does the plasma membrane control
What substances enter + leave cells
What’s a plasma membrane made up of
A phospholipid bilayer
2 parts of a phospholipid
Phosphate group (head) Fatty acids (tails)
What part of phospholipid is hydrophilic + hydrophobic
Phosphate group - hydrophilic (loves water)
Fatty acids - hydrophobic (hate water)
What’s embedded into the plasma membrane
Proteins
3 types of proteins embedded in plasma membrane
Ion - channel proteins
Transport proteins
Glycoproteins
What do ion-channel proteins allow
E.g
Allow some ions to pass through the membrane
E.g Na, K, Fe
What can ion-channel proteins not carry
Insoluble things (hydrophobic)
What do transport proteins do
Carry molecule in + out of the cell
What do transport proteins use
What process are they involved in
Use ATP
Involved in active transport
What’s the word for ‘in the membrane ’
Instrinsic
What do glycoproteins do
Act as markers so that the cell can be recognised (antigens)
2 things that stick out of membranes
Glycoproteins
Glycolipids
How do you notice glycoproteins on membrane diagrams
They are slightly larger and are attached to proteins
What’s the word for ‘sticks out of membrane’
Extrinsic
How do glycoproteins help a group of cells
Help them attach to each other, forming cell tissue
What do glycolipids help to determine
Blood type
What are glycolipids made up of
Carbohydrates bound to lipids
2 ways glycolipids are helpful
Help stabilise the membrane
Help cells attach to one another
How does cholesterol benefit a membrane
Adds strength (holds together tails )
Why does cholesterol help reduce water loss from the bilayer
As it’s very hydrophobic
What does having cholesterol in a membrane reduce and how
Reduces movement as it pulls together the lipid tails
What’s the model that shows what’s in a membrane called
The fluid mosaic model
Why’s it called ‘fluid’ ‘mosaic’ model
Fluid - slight flexibility as phospholipids move relative to each other
Mosaic - embedded throughout membrane
What’s another name for channel proteins
Channel proteins
What’s another name for transport proteins
Carrier proteins
Why are channel proteins hydrophilic
What are they like
For water + other polar molecules to pass through
Are like pores/holes in the membranes
What do carrier proteins use to open them
ATP for active transport to open them
What do carrier proteins have similar to enzymes
Specific binding sites for certain substances, their shape has to be complementary to a specific substance
What are chloroplasts in
Plants + algae
What system are chloroplasts not part of
The endoplasmic reticulum system
Why are chloroplasts independent like mitochondria
They have their own DNA + ribosomes
What’s the green pigment called that chloroplasts contain
What’s it important for and why
Chlorophyll
Important for photosynthesis as it absorbs sunlight
What’s 1 flattened membrane sac in a chloroplast called
What’s a stack of them called
Thylakoid
Granum
What part of chloroplasts does photosynthesis take part in
Thylakoids
Why are thylakoids arranges in stacks
So they are compact and more can be fitted in , so more chlorophyll, and more photosynthesis
What’s the fluid inside a chloroplast called that contains DNA + ribosomes
Stroma
What 2 things is the stroma in chloroplasts the site of
The site of chemical reactions + sugar production (food)
3 things the cell wall does
Protects cell
Maintains shape
Prevents excessive water uptake/loss
What do cell walls contain
Cellulose (sugar) , proteins + carbohydrates
What are the 3 layers of a cell wall
The middle lamella
The primary cell wall
The secondary cell wall
Which layer of the cell wall is stretchy
The middle lamella
What’s the middle lamella
The first layer of the cell wall formed after cell division (cell still a baby)
Is the connecting boundary
What’s the middle lamella made from
Pectin
Protein
Why does the middle lamella allow the cell to grow
As it isn’t rigid
When does the primary cell wall form
After the middle lamella
Why is the primary cell wall more rigid than middle lamella
As it contains cellulose fibres that make it more rigid
2 thinks the primary cell wall contains other than cellulose
Pectin (carbohydrate)
Glycoproteins
What cell wall causes the cell not to grow anymore once it’s formed
The secondary cell wall
When is the secondary cell wall formed
What does it contain often
When the cell is mature
Often contains layers
3 things the secondary cell wall is made up of
Cellulose
Hemicellulose
Lignin (in woody plants)
What’s the biggest part of a plant cell
Vacuole
What does a permanent vacuole contain
Cell sap
What’s a vacuoles single membrane called
Tonoplast
5 things a vacuoles fluid contains
Minerals Sugars Amino acids Waste products Pigments (anthocyanins)
3 uses of a vacuole
Keeps cell turgid (firm)
Stores waste products that may damage the cell
Acts as a food store
What do the pigments in a vacuole do
Add colour to petals
What type of compounds does a vacuole contain
Poisonous/unpalatable compounds
What’s the process called when cells can do specific functions
Specialisation
What are specialised cells organised into
Tissues -> organs -> organ systems
