Cell Structure And Function Flashcards
What is the cell theory?
A theory that states:
All living things are made of cells and their products
New cells are created by old cells dividing in two
Cells are the basic building blocks of life
How did cell theory come about?
Developed by two microbiologists Schleiden and Schwann in 1839
What are the units within cells?
Organelles
What do cells group together to form?
Tissues
What do tissues group together to form?
Organs
What do organs group together to form?
Organ systems
What do organ systems group together to form?
Organisms
What is the smallest unit of life?
Cells
How can you tell the difference between the Golgi body and the endoplasmic reticulum?
The ER will be attached to either the cell membrane, or the nucleus
The Golgi body will not be attached to anything
Where is the nucleus situated in an animal cell?
In the centre
Where is the nucleus situated in a plant cell?
Near the side
The vacuole takes up the centre space
What do all cells have in common?
Cell membrane
Cytoplasm
DNA
What kinds of cells are prokaryotic?
Unicellular organisms
What are the two parts of a cell?
Living
Non-living
What is between cell walls in a plant?
The middle lamela
What is lignin like?
Thick, strong and waterproof
What is another name for a cell membrane?
Plasma membrane
What model describes what the cell membrane looks like?
Fluid-mosaic-model
What is a cell membrane made of?
Phospholipid bilayer
Protein
Carbohydrate chains attached to it
What is the phospholipid bilayer like?
Has hydrophilic fatty acid tails
Has hydrophobic glycerol heads
What do the proteins in the cell membrane do?
Help with active and facilitated diffusion
What are the carbohydrate chains in the cell membrane for?
Communication
What is the main function of the cell membrane?
To control what comes into the cell and what goes out of the cell
What are some other functions of the cell membrane?
Transport of nutrients Ingestion Excretion Strength of membrane allows mechanical support Flexibility allows growth and movement
What is cytoplasm made of?
90% water
Dissolved nutrients and waste
What does the cytoplasm do?
It exerts pressure on the cell membrane (structure)
Holds nourishment for the organelles
Suspends the organelles
Can be a storage area
What does the nucleus contain?
Chromatin network
Nucleolus
Nucleoplasm
Nuclear membrane
What does the nucleolus do?
Makes RNA (ribosomes) which make proteins
What is nucleoplasm?
The jelly-like liquid inside the nucleus
What is the nuclear envelope?
A double membrane surrounding the nucleus
Is selectively permeable
What do nuclear pores do?
Allow substances into the nucleus
What does DNA do?
Contains hereditary information
Contains the “code of life” (tells ribosomes what proteins to make)
Where does the DNA in the mitochondria come from?
Only from the mother of an organism
What are the two types of ER?
Rough
Smooth
What does the rough ER do?
Protein synthesis
Membrane production
What does the smooth ER do?
Lipid synthesis
What is the difference between the rough and smooth ER?
Rough has ribosomes
Smooth does not
What are the two types of ribosomes?
Free ribosomes and polyribosomes
What makes vesicles?
Golgi body
ER
Cell membrane
When are lysosomes usually produced?
When a cell dies
When an animal cell has lots of food vacuoles
What is a ‘floppy’ vacuole called?
Flaccid
What is the difference between cells called?
Differentiation
What is specialisation?
When cells change to perform a specific function
What kinds of functions might a cell preform?
Muscle cells contract and relax
Nerve cells conduct impulses
Glandular cells secrete substances
What is protoplasm?
The living material in plant and animal cells
What are all cells made up of?
Protoplasm
What is a cell wall?
A non-living component that animal cells do not have
What does protoplasm consist of?
Cytoplasm
Nucleoplasm
What is cytoplasm enclosed by?
The cell membrane
What is an organelle?
A membrane-bound structure that is found in the cytoplasm of a cell and that performs a specific function
What is the only non-living part of a cell?
The cell wall
What are the three parts of the cell wall?
Primary cell wall
Middle lamella
Secondary cell wall
What is a primary cell wall?
The first layer in the cell wall
Where does the primary cell wall occur?
On the outside of the cell membrane
How thick is the primary cell wall?
It is thin
What is the primary cell wall made of?
Cellulose fibres that can stretch as the cell grows
What is responsible for communication (and transportation) between plant cells?
Pits
And plasmodesmata
What are pits?
Small openings in the cell wall
What are plasmodesmata?
Cytoplasmic threads that extend through the pits to adjacent cells
What is the middle lamella?
The substance that connects cell walls to one another
Where does the middle lamella occur?
Outside the primary cell wall
What is the middle lamella made of?
Pectin
What is pectin?
A soluble, jelly-like polysaccharide
It is quite sticky
When does the secondary cell wall develop?
As the cells grow older
What does the secondary cell wall consist of?
Cellulose fibres
Lignin
What is lignin?
An organic substance that joins cellulose to one another in woody tissues
What does lignin do?
Thickens and strengthens the cell walls
What are the properties of the secondary cell wall?
It is inelastic
What are the pits of the secondary cell wall like?
They are deeper
Also have plasmodesmata
What is the permeability of the cell wall like?
Completely permeable
What is the function of the cell wall?
Support structure
Protects the living contents of the plant cell
Gives rigidity to the plant
What is sol cytoplasm?
The cytoplasm in a liquid state
What is gel cytoplasm?
Cytoplasm in a jelly-like state
What is the sol cytoplasm called?
The ground substance (hyaloplasm)
What does the ground substance look like?
It looks grey but is actually clear
Why does the ground substance look grey?
Due to the organelles and dissolved substances in it
What is the function of cytoplasm?
It is the site of all metabolic processes
Cyclosis
Storage
Helps to maintain the shape of the cell
What is cyclosis?
The movement of cytoplasm, specifically to circulate substances throughout the cell
What is the cell membrane?
The outer living boundary of the cytoplasm
In an animal cell, it also protects the contents of the cell
Why are there proteins embedded in the cell membrane?
For transportation
Which part of the phospholipid molecule face inwards?
The tail
Which part of the phospholipid faces outward?
The head
Why is the cell membrane referred to as fluid?
It is not static (it can move)
What is the permeability of the plasma membrane like?
It is selectively permeable
Which substances is the phospholipid bilayer impermeable to?
Water-soluble molecules
What are examples of water-soluble molecules?
Glucose
Amino acids
Salts
Nucleic acids
How do water soluble molecules move through the cell membrane?
Carrier proteins pick them up and drop them on the other side
What do other proteins (that pass through the phospholipid bilayer) do?
Form small channels which will only allow certain ions through
What are the main compounds that make up cells?
Proteins Carbohydrates Lipids Nucleic acids Water
What are the two types of cells?
Prokaryotic
Eukaryotic
What is a prokaryotic cell?
A cell in which there are no membrane-bound organelles i.e. Do not have a nucleus
What is a eukaryotic cell?
A cell in which there are membrane-bound organelles i.e. Do have a nucleus
What is an example of a prokaryotic cell?
Bacteria
What are the two types of eukaryotic cells?
Animal
Plant
What kind of surface area is optimal for a cell?
A large surface area is best
Why do cells need a large surface area?
It facilitates the movement of substances into and out of the cell
What is the optimal volume for a cell?
Relatively small
Why must the volume of a cell be relatively small?
It allows for easy diffusion of substances within the cell
Are all cells the same?
No, their size, shape and structures change
What two forms can cytoplasm exist in?
Sol
Gel
What does the nucleolus look like?
It is a dark body
What is the chromatin network?
Tangled threads of DNA
What are chromosomes?
Structures that consist of DNA and histones
What is the function of the nucleus?
Controls all of the activities of the cell
Contains DNA
What does a mitochondrion look like?
A cylindrically-shaped hollow rod
It has a double membrane
What does the inner membrane of the mitochondrion look like?
It has folds, known as cristae, to increase surface area
What is the matrix?
A semi-fluid substance that fills all mitochondria
Why does the matrix contain ribosomes?
They synthesis the enzymes that help with the chemical reactions within the mitochondria
What is the function of the mitochondria?
Cellular respiration
What is cellular respiration?
The process whereby glucose is transformed and energy is released
What kind of energy does the cell use?
ATP energy
Adenosine triphosphate
What affects the amount of mitochondria in a cell?
How much energy that cell needs
What kind of cell will have more mitochondria?
A muscle cell
What are ribosomes?
Small spherical structures that occur in plant and animal cells
What do ribosomes consist of?
RNA and proteins
Where do ribosomes occur?
ER
Mitochondria
Chloroplasts
In groups in the cytoplasm
What are polyribosomes?
Ribosomes that occur in groups in the cytoplasm
What is the function of ribosomes?
Protein synthesis
What is protein synthesis?
The process during which 51 or more amino acids join to form a protein
What is the ER?
A fine membranous network found in plant and animal cells
It forms a continuous system of canals throughout the cytoplasm
What does ER stand for?
Endoplasmic Reticulum
Where does the ER occur?
Either connected to the plasma membrane or to the nuclear membrane
What is the function of the ER?
Transports substances from one part of the cytoplasm to another
Increases the internal surface area of the cell
What does the Golgi body look like?
Stacks of hollow, flat membrane sacs
These are called cisternae
Where does the Golgi body occur?
Plant and animal cells near the nucleus
What kind of cells will have more Golgi bodies?
In cells that have a secretory function
What is the function of the Golgi body?
It plays a role in producing and processing secretions
It prepares proteins for transport to other parts of the cell
What are examples of secretions that the Golgi body might produce?
Mucous
Saliva
What are plastids?
A type of organelle that occurs only in plant cells
What are the three types of plastids?
Chloroplast
Chromoplast
Leucoplast
What do chloroplasts look like?
Oval-shaped
Surrounded by a double membrane
Where do chloroplasts occur?
In photosynthesising parts of the plant i.e in the leaves
What is stroma?
A fluid matrix that fills the chloroplast
What are thylakoids?
Disc-shaped membranes that are contained in the stroma
What is a granum?
A stack of thylakoids
What is the plural form of granum?
Grana
What is another name for thylakoids?
Lamellae
What connects two grana?
A membrane known as the intergranum
What is another name for the intergranum?
The middle lamella
What is embedded in the thylakoids?
Chlorophyll
What else does the stroma contain?
Enzymes
Starch grains
Oil droplets
Ribosomes
What is the function of the chloroplast?
Photosynthesis
What is photosynthesis?
The process whereby radiant energy from the sun is converted into starch granules
What is the formula for photosynthesis?
Radiant energy
H2O + CO2 —————-> C6H12O6 + O2
Chlorophyll
What is the formula for cellular respiration?
C6H12O6 + O2 –> H2O + CO2 + ATP energy
What are chromoplasts?
Plastids that give plants their orange, red or yellow colour
How do chromoplasts occur?
Chloroplasts change into chromoplasts when autumn comes or when fruit ripens
How do chromoplasts change the colour of the plant?
With pigments
What are chromoplast pigments called?
Carotenoids
Why do plants need colour?
To attract bees and birds for pollination
What are leucoplasts?
Colourless plastids
Where do leucoplasts occur?
In cells that store food in an insoluble form
What is the function of leucoplasts?
They become specialised to store food in the form of starch, lipids or proteins
What can happen if leucoplasts are exposed to light?
They can turn into chloroplasts
What are vacuoles?
Fluid-filled compartments in the cytoplasm
What encloses the vacuole?
A membrane called the tonoplast
It is selectively permeable
What is the fluid inside a vacuole called?
Cell sap
What is cell sap made of?
Water and dissolved nutrients
What are vacuoles like in plant cells?
Large and prominent
What are vacuoles like in animal cells?
Small or absent
What is it called when the vacuole is not floppy?
Turgid
What is the function of the vacuole?
Rigidity
Colouring (blue, violet and purple)
How does vacuole give the cell rigidity?
It exerts turgor pressure on the cell
How does the vacuole give colour to the plant?
Through pigments in the cell sap
What are the pigments in cell sap called?
Anthocyanins
What are four other types of vacuoles?
Contractile vacuoles
Food vacuoles
Vesicles
Lysosomes
Where do contractile vacuoles occur?
In unicellular animals
What do contractile vacuoles do?
Play a role in osmoregulation
What is osmoregulation?
Maintaining water balance
Where do food vacuoles occur?
In simple animals
What do food vacuoles do?
Play a role in the digestion and storage of food
What is the size of vesicles?
Vesicles are small
What do vesicles do?
Play a role in the transportation of substances from the Golgi body to parts inside and outside the cell
What are lysosomes?
Small vacuoles that are filled with digestive enzymes
Where do lysosomes occur?
Only in animal cells
What do lysosomes do?
Food digestions, particularly in unicellular animals
How do lysosomes digest food?
They fuse with food vacuoles and release the enzymes that digest the food
Where do centrosomes occur?
Only in animal cells
In the cytoplasm near the nucleus
What do centrosomes consist of?
Two small cylindrical structures known as centrioles
How are the centrioles positioned?
They are close to one another at lie at 90° to each other
What does a centriole consist of?
Fibrils
What does a fibril consist of?
Three tubular structures known as microtubles
What is the function of the centrosome?
The centrioles play a role in mitosis when they form spindle fibres
What is the difference between plant and animal cells concerning the cell wall?
Animal: absent
Plant: present
What is the difference between plant and animal cells concerning plastids?
Animal: absent
Plant: present
What is the difference between plant and animal cells concerning vacuoles?
Plant: large
Animal: small or absent
What is the difference between plant and animal cells concerning lysosomes?
Plant: absent
Animal: present
What is the difference between plant and animal cells concerning centrosomes?
Plant: absent
Animal: present
What is the difference between plant and animal cells concerning shape?
Plant: fixed
Animal: irregular
