Cells Flashcards
What are cells?
Cells are the smallest structural and organisational unit of which all living things are built upon
What are organelles?
Any of the specialised structures in a cell. Each has a specific structure that suits its specific functions
What are the characteristics of prokaryotic cells?
Small
Simple
No true nucleus
No membrane bound organelles
unicellular(often live in colonies)
What’s an example of prokaryotic cells?
Bacteria
Archaea
What are membrane bound organelles?
Organelles that are bound by membranes
What are the characteristics of Eukaryotic cells?
Large
Complex
Has a nucleus
Membrane bound organelles
multicellular
What is an example of Eukaryotic cells?
Plants
Animal
fungi
What is the difference between prokaryotes and eukaryotes?
Prokaryotes are always unicellular, while eukaryotes are often multi-celled organisms. Eukaryotes have a nucleus whereas prokaryotes do not have a nucleus.
What is a prokaryotic cell?
It is a primitive cell characterised by the absence of nucleus, prokaryotes do not have membrane bound organelles and are exclusively unicellular
What is an eukaryotic cell?
These cells possess a true nucleus and have membrane bound organelles. They are either unicellular or multicellular
What is cell theory?
- All organisms consist of cells or products of cells
- All cells come from preexisting, by the process of cell division
- Cells are building blocks of life
What are living things called? What can they be?
All living things are called organisms and they can be either unicellular or multicellular
What is the basic concept and purpose of a cell?
Cells provide the structure of an organism and carry out life process of living things
What are the functions of a cell membrane?
- Bilayer of phospholipids
- Encloses the cytoplasm
- Controls the movement of substances into and out of cells
- Responsible for:
↳ recognition
↳adhesion
↳chemical communication - Controls what enters and leaves the cell
- Selects molecules in and out, keeps things inside the cell stable
What are the functions of cytoplasm?
- Surrounding fluids
- Provides a platform upon which other organelles can operate within the cell.
- For cell expansion, growth and replication are carried out in the cytoplasm of a cell
What are the functions of ribosomes?
- The site of protein synthesis
- Makes protein
- Is found on rough E.R or free floating
What are the functions of the nucleus?
- Contains genetic material (DNA)
- Controls the activity of the cell
What are the functions of endoplasmic reticulum?
It may be rough with with ribosome- site of protein synthesis
It my be smooth with no ribosomes
Is involved with the production, processing, transport and storage of materials within the cell
Processes of molecules
What are the functions of mitochondria?
Are involved in cellular respiration where energy is transformed and release be cells
Makes ATP in a process of cellular respiration
What is the worded formula for mitochondria?
Glucose + oxygen → carbon dioxide + water + energy
What is the equation for mitochondria?
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
What are the functions of the cell wall?
- Provides support
- Prevents expansion
- Attains shape
What are the functions of chloroplast?
- Found only in plant cells
- They are green as they contain chlorophyll
- Site of photosynthesis
What is the worded formula of photosynthesis?
Water + carbon dioxide → glucose oxygen
What is the worded formula of photosynthesis?
Water + carbon dioxide → glucose oxygen
What is the equation for photosynthesis
6H2O + 6CO2 →sunlight→ C2H2O6 + 6O2
What are the functions of vacuoles in plants?
Maintains water balance
What are the functions of vacuoles in animals?
Help isolate waste
What are the organelles in an animal cell
ribosome
mitochondria
Cell membrane
lysosome
cytoskeleton
cytoplasm
nucleus
vacuole
Golgi body
Endoplasmic reticulum
What are the organelles in a plant cell?
ribosome
mitochondria
Cell membrane
Golgi body
chloroplast
cytoskeleton
Nucleus
nucleolus
vacuole
Cell wall
cytoplasm
lysosome
Endoplasmic reticulum
What are the functions of the Golgi apparatus?
A stack of flat membrane sacs
Where the final synthesis and packaging of proteins occur
Is linked to the endoplasmic reticulum
What is the difference between animal and plant cells?
Plant cells have a cell membrane surrounded by a cell wall; animal cells do not
Plants cells may carry membrane-enclosed organelles called chloroplast; animals do not
Plant cells have a small number of large, permanent vacuoles: animal cells do no
The cells or all bacteria is called prokaryotic cells, they usually have?
Have a cell wall that surrounds the cell membrane
Carry DNA in the cytoplasm where it is organised into a single circular chromosome
Contains simper- sub cellular components that lack a membrane
Exist as single cells or are unicellular
What shapes do prokaryotes come in?
Spheres, rods and spirals
How do prokaryotic cells carry DNA without a nucleus?
Prokaryotic cells carry DNA in the cytoplasm where it is organised into a singular circular chromosome
Describe the nucleus:
Surrounded by a double layer nuclear membrane
Contains pores that allow the nucleus to communicate with the cytoplasm
Contains genetic material (DNA)
Controls the activities of cells
Describe the cell wall?
Non-living, cellulose structure
Provides support
Prevents expansion of the cell
Allows water and dissolved substances to pass through it
Describe the vacuole?
Membrane bound
Found in variable numbers
Contain food, enzymes and fluid
In plant cells, vacuoles are quite large and aid in providing support to the cell
In animals cell they are small and numerous
Describe the vesicle?
Membrane bound
Associated with the transport of substance within cells
Describe the lysosomes?
Found in most animal cells
Are membrane bound vesicles
Contain powerful enzymes that break down debris and foreign material
Eukaryotic cells usually:
Carry DNA in a nucleus where it is organised into a set of linear chromosomes
Contains a variety of subcellular components called membrane- enclosed organelles
Exist with large number of similar cells by may exist as single cells
Are significantly larger than prokaryotic cells
How do eukaryotic cells differ in plants and animal cells?
- Plant cells have a cell membrane surrounded by a cell wall; animal cells don’t
- Plant cells have a small number of large, permanent vacuoles; animal cells do not
- Plant cells may carry membrane enclosed organelles called chloroplasts; animal cells do not
What functions do membrane enclosed organelles in eukaryotic cells have?
- Making important biological molecules (eg:protein)
- Performing biochemical reactions (eg: aerobic cell respiration and photosynthesis)
- Secretion of substance made by the cell (eg:protein)
- Removal of wastes (eg: carbon dioxide)
What happens during the process of cellular respiration?
The mitochondria creates ATP molecules that provide the energy for all cell and when cells need more energy they will contain more mitochondria
Eukaryotic cells usually…
Carry DNA in a nucleus where it is organised into a set of linear chromosomes
Contains a variety of subcellular components called membrane enclosed organelles
Much larger than pro cells
Is the cell wall membrane-enclosed?
no
Is the cell membrane membrane-enclosed?
no
Is cytoplasm membrane-enclosed?
no
Is ribosome membrane-enclosed?
no
Is the nucleus membrane-enclosed?
yes
Is rough E.R membrane-enclosed?
yes
Is smooth E.R membrane-enclosed?
yes
Is the golgi body membrane-enclosed?
yes
Is mitochondria membrane-enclosed?
yes
Is vacuole membrane-enclosed?
yes
Is chloroplast membrane-enclosed?
yes
What does E.R stand for?
Endoplasmic reticulum
What are a few of the functions organelle in eukaryotic cells do?
- Make important biological molecules (protein)
- Performing biochemical reactions (like aerobic cell respiration and photosynthesis)
- Removal of substance made by the cell
- Removal of waste
What are the structural features and special function of ribosomes?
Structural feature- tiny non-membrane bound organelle
Special function- site of protein synthesis
What are the structural features and special functions of a cell wall?
Structural feature- wall outside of cell membrane, made up of sugars and amino acids
Special function- provide support and structure for the unicellular organism
What are the structural features and special functions of cell membranes?
Structural feature- phospholipids and membrane proteins
Special functions- controls entry and exit of materials
What are the structural features and special function of chromosomes?
Structural features- consists of one circular chromosome
Special functions- genetic information of bacteria
Is the nucleus in plant or animal cells?
both
Is the golgi body in plant or animal cells?
both
Is the mitochondria in plant or animal cells?
both
Is chloroplast in plant or animal cells?
Is chloroplast in plant or animal cells?
Some plant cells only
Are vacuoles in plant or animal cells?
both
Is the endoplasmic reticulum in plant or animal cells?
both
What are the structural features and special functions of the nucleus?
Structural features-membrane bound, contains pores
Special functions- contains DNA chromosomes, genetic material
What are the structural features and special function of golgi bodies?
Structural features- stacks of flattened structures
Special functions- packaging and secretion of molecules
What are the structural features and special functions of mitochondria?
Structural features- double membrane, contains many enzymes
Special functions- site of aerobic respiration
What are the structural features and special function of chloroplast?
Structural features-contains the pigment chlorophyll
Special functions- site of photosynthesis
What are the structural features and special function of vacuoles?
Structural features- larger and more central in plants
Special functions- storage of water and ions in plants
What are the structural features and special function of endoplasmic reticulum?
Structural features- network of membranous structures in cytoplasm
Special functions- internal transport of molecules
Prokaryotic cells do not contain membrane-enclosed organelles. How it is possible for them to grow, divide and make energy available
They do it because…
- Prokaryotic cells contain DNA but not in a nucleus
- They have chemicals for metabolism and transformation of energy
- They are simpler cells with less internal organisation
Where would mitochondria be found?
Active muscle cells (heart, sperm cells)
Where would chloroplast be found?
In leaves and plants
Where would the golgi body be found?
In the respiratory tract where they secrete mucus (lungs and trachea)
Is the cell wall Prokaryotes?
yes
Is the cell membrane Prokaryotes?
yes
Is the nucleus Prokaryotes?
no
Is mitochondria Prokaryotes?
no
Is chloroplast Prokaryotes?
no
Is the vacuole Prokaryotes?
no
Is lysosome Prokaryotes?
no
Is cytoskeleton Prokaryotes?
yes
Are ribosome Prokaryotes?
yes
Is E.R Prokaryotes?
yes
Is the cell wall in eukaryotes cells for animals or plants?
plant
Is the cell membrane eukaryotic cells for animals or plants?
both
Is the nucleus eukaryotes cells for animals or plants?
both
Are mitochondria eukaryotic cells for animals or plants?
both
Are chloroplast eukaryotic cells for animals or plants?
plant
Are vacuole eukaryotic cells for animals or plants?
both
Is lysosome eukaryotic cells for animals or plants?
both
Are cytoskeleton eukaryotic cells for animals or plants?
both
Are ribosome eukaryotes cells for animals or plants?
both
Are E.R eukaryotes cells for animals or plants?
both
What is the cell requirement?
When cells required energy for different functions
What are the three functions of cell requirement in detail?
movement
- Most cells can move or change shape
synthesis
- Cells require energy to break down and build up molecules
Stable internal environment
- Cells need activity regulate concentration for various subraces in cells
What are energy producers?
Organisms which are capable of producing their own energy and are called autotrophs
What are autotrophs?
Organisms that are able to produce their own energy
What are the two different types of autotrophs?
Chemosynthetic autotrophs
Photosynthetic autotrophs
What are chemosynthetic autotrophs?
Derive their energy from inorganic sources such as sulphur or ammonia (come bacteria are chemosynthetic)
What are photosynthetic autotrophs
Convert light energy into chemical energy (eg, plants- in plants photosynthesis takes place in membrane- bound organelles called chloroplast)
What are chloroplasts filled with?
Chloroplasts are filled with a green pigment called chlorophyll. This is what gives plants their green colour
In photosynthetic bacteria the reaction…
Of photosynthesis takes place within the cell itself, not within a discrete organelles
Where is chloroplast located in plant leafs?
In the plant cells in the upper surface of leaves have chloroplast
What happens through photosynthesis
Through this process the plants can make glucose (sugar) and as a byproduct, it produces oxygen
What is the process of photosynthesis?
It is the process of transforming sunlight energy into chemical energy
What is photosynthesis produced?
- Energy for use by the autotroph and for use later down the food chain
- Oxygen gas is essential for the survival of advanced life forms
Where is aerobic respiration?
It is in the mitochondria located in both plants and animals
What formula is thisC6H12O6 + 6O2 yields 6CO2 + 6H2O + energy
Aerobic respiration
What is the equation for aerobic respiration?
C6H12O6 + 6O2 yields 6CO2 + 6H2O + energy
What is the word formula for aerobic respiration?
glucose + oxygen → carbon dioxide + water (+ ATP made)
Aerobic respiration is with ______?
oxygen
Anaerobic respiration is ______________?
fermentation
Anaerobic respiration is with ______?
Out oxygen
What is the plant equation for Anaerobic respiration?
C6H12O6 ⟶ 2C2H5OH + CO2 + ATP
What is the plant’s worded equation for Anaerobic respiration?
Glucose →ethanol + carbon dioxide + energy
What is the surface area to volume ratio in a cell membrane?
Cells need to exchange materials for survival
The more efficiently the exchange, the better the chance of survival
Cells make exchange efficient by increasing the surface area to volume
Where do cells exchange materials?
Cells exchange material with the part of the cell in contact with the environment
This occurs through the cell membrane
The cell membrane is semi permeable:
This means that only certain molecules can cross in certain ways
The cell membrane is impermeable to:
- Water soluble molecules
- Ions (overall positive and negative charge)
- Polar molecules
The cell membrane is permeable to:
Lipids soluble substance of various sizes
Tiny molecules such as water or urea
Small uncharged molecules
What are the hydrophilic heads of the cell membrane?
These are in constant contact with water later in the extra (outside) cellular fluid and the cytoplasm
What are the hydrophobic tails of the cell membrane?
These are arranged together protected on both sides by the hydrophilic heads
What do lipid molecules do?
What do lipid molecules do?
They can pass by molecules that are the same
What can small molecules do?
(even water) can pass as they can get by without touching the lipids tails
What is water soluble?
It is the molecules cannot pass through the middle of the membrane as the middle does not like water
What are Ions and polar molecules in a cell membrane?
Interacted with water but are unable to interact with non polar lipids so also cannot pass through the middle membrane
How do water solubles, ions and polar molecules travel as they can not pass directly through the membrane?
- Through the protein channels
- These span the whole membrane and are called transmembrane proteins
- These use active transport
How is cholesterol a component of the cell membrane?
Increases the stability (maintaining structure) and fluidity of the cell membrane
How are carbohydrates a component of the cell membrane?
It allows the cells communications and adhesion between cells
What is the movement of molecules?
- Every cell is surrounded by a cell membrane that is selectively permeable
- The membrane structure allows substances to cross it by 2 means- active and passive transport
What is passive transport?
- Diffusion and osmosis
- Allows movement of substances like wat and gases in and out of the cell without the use of energy
What is active transport?
Ion pumps, exocytosis, pinocytosis and phagocytosis
What are substances in the cell molecules eg sucrose?
- The are too big to pass through the membrane
- Have unfavourable characteristics to pass through the membrane
- Are being moved against their concentration gradient
What is a concentration gradient?
Is exists whenever two areas have different concentrations of a substance
All movement of the molecules required?
Additional energy
What is fermentation?
It is produced by ATP by producing energy released by breaking down glucose without oxygen
What are the two different types of fermentations?
Alcohol and lactic acid fermentation
Where does lactic acid fermentation occur
In animal cells where there are insufficient quantities of oxygen to carry out aerobic respiration nay faster
What is autotroph?
an organism that can produce its own food using light, water, carbon dioxide, or other chemicals
What is heterotroph?
an organism that eats other plants or animals for energy and nutrients
What is photosynthesis?
Green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a by-product.
What is respiration?
Respiration is defined as a metabolic process wherein, the living cells of an organism obtains energy
What is fermentation?
the process in which a substance breaks down into a simpler substance
What is metabolic waste?
the end products of metabolism or protein metabolism. These products are toxic and has to be eliminated from the body
What is excretion?
the process by which organisms expel metabolic waste products and other toxic substances from their body.
What is urea?
reacting natural gas, atmospheric nitrogen and water together at high temperature and pressure to produce ammonia and carbon dioxide.
What are organic molecules?
Organic molecules are molecules that are made of carbon and hydrogen, and can include other elements.
What are inorganic materials?
Inorganic materials are defined as chemical compounds that contain no carbon
What is chemoautotroph?
Chemoautotrophs are organisms that obtain their energy from a chemical reaction
What are photoautotrophs?
a photosynthetic organism that utilises energy from light to synthesise organic molecules.
What is the surface area to volume ratio for cells?
- Cells need to exchange materials for survival
- The more efficient the exchange the better the chance of survival is
- Cells make exchange efficient by increasing their surface area to volume ratio
How do cells exchange material?
With the parts of the cell in contact with the environment- this occurs through the cell membrane
What is semi-permeable, give an example of where it would happen?
Semi-permeable means that inly certain molecules can cross in certain ways- this happens in the cell membrane
Cell membranes are impermeable to….
- Water soluble molecules
- Ions (overall positive & negative charge)
- Polar molecules (no overall charge)
Cell membranes are permeable to….
- Lipids soluble substances of various sizes
-Tiny molecules such as water or urea
-Small uncharged molecules
What’s hydrophobic tails and where are they located?
They are arranged together protected on both sides by the hydrophilic heads. It is the cell membrane.
Can lipid molecules pass through the Hydrophilic heads and hydrophobic tails?
It can pass by molecules that are the same
Can small molecules pass through the Hydrophilic heads and hydrophobic tails?
(even water) can pass as they can get by without touching the lipid tails
What is water soluble:
Molecules cannot pass through the middle of the membrane as the middle does not like water
What are ions and polar molecules?
Interact with water but are unable to interact with non polar lipids so they can also cannot pass through the middle of the membrane
Since water solubles, ions and polar molecules ____?
Cannot pass directly through the membrane, they can use protein channels
Protein channels span the whole membrane and are called??
Transmembrane proteins- they uses active transport
What is cholesterol in the membrane?
Is the increases of the stability (maintaining structure) and fluidity of the cell membrane
What are carbohydrates in the cell membrane?
Allows cells communications and adhesion between cells
What is every cell surrounded by?
A cell membrane that is selectively permeable
What does the membrane structure allow?
It allows substances to cross it by 2 means:
- Passive transport
- Active transport
What is passive transport?
It is diffusion and osmosis
- It allows the movement of substance (eg, water and gases) in and out of the cell without the us of energy
What is active transport?
Ion pumps, exocytosis, pinocytosis and phagocytosis
Substances like sucrose are…..?
- Are too big to pass through the membrane
- Have unfavourable characteristics to pass through the membrane
- Are being moved against their concentration gradient
What is a concentration gradient?
It exists whenever two areas have different concentration of the substance
What is the fluid mosaic model?
Fluid- the phospholipid bilayer- this can move around the cell membrane like liquid
Mosaic- it is all these little random hard structures floating around the cell membrane
What does solute mean?
The substance being dissolved
What does solvent mean?
The substance doing the dissolving
What does the solution mean?
A combination of a soluble solute and solvent
What is diffusion?
It’s the passive movement of a solute from a region of high concentration to a region of low concentration across a semipermeable membrane until equilibrium is reached (have to remember word for word)
What is osmosis (passive transport)?
It’s the passive movement of a water (solvent) from a region of a high concentration to a region of low concentration across a semipermeable membrane until equilibrium is mede (have to remember word for word)
Osmosis is the _____?
Passive movement of a water (solvent) from a region of low solute (high water) concentration to a region of high solute (low water) concentration
What is active transport using trans-membrane protein?
Active transport requires the use of energy to move molecules
When are Trans-membrane proteins used when molecules?
- Are too big (with or against a concentration gradient)
- Need to move against their concentration gradient
- From low to high concentration
What is Endocytosis?
Moving into the cell
What is Phagocytosis?
Solid particles
What is Pinocytosis?
Liquid particles
What is facilitated diffusion?
It is selected solutes that go from high concentration to low concentration across the across the semipermeable membrane through the protein until equilibrium is reached
What is facilitated diffusion?
It is selected solutes that go from high concentration to low concentration across the across the semipermeable membrane through the protein until equilibrium is reached
What is passive movement?
Diffusion, osmosis, facilitated diffusion
What is active movement?
Active transport, endocytosis, exocytosis
What is hypertonic?
When h2O exits the plant cell
What is isotonic?
When H2O enters and exits the plant cell
What is hypotonic?
When H2O enters the plant cell
Diffusion is ….?
is the passive movement of a solute from
a region of high concentration to a region of low concentration across a semipermeable membrane until equilibrium is reached.
Why can CO2 be considered a metabolic waste product from human cells but not from plant cells?
Carbon dioxide is a by-product from aerobic respiration. Carbon dioxide in plants is a raw material for photosynthesis
Name three factors that may alter the rate of photosynthesis with a short explanation
- Temperature will affect the rate of chemical reaction within the cells
- Light intensity is important because light provides energy for photosynthesis
- Carbon dioxide level is important since it is a raw material for the process
Why do cells need to exchange materials?
Cells must exchange materials with their external environment to survive; for example glucose and oxygen are obtained from the external environment
Why do cells need to exchange materials?
Cells must exchange materials with their external environment to survive; for example glucose and oxygen are obtained from the external environment
What are some materials exchanged across the cell membrane?
-Gases
-Nutrients
-Waste procust
What are factors that can affect whether a substance will pass across the cell membrane?
Size- only small molecules are freely exchanged
Charge- ions, can only be exchanged if specific membrane proteins called membrane transport proteins
Solubility in water- water and hydrophilic molecules can only be exchanged if specific membrane transport proteins are used too
What is passive transport?
According to the kinetic model, atoms and molecules are in a state of constant, random motion, this causes them to collide so often there is a gradual net movement away from where the atoms or molecules are most concentrated to where they are least concentrated this is called passive transport.
What is an example of passive transport?
The movement of water across membranes between regions that have different solute concentrations is another example of passive transport.
What factors affect the rate of exchange of materials at the cell membrane?
-Surface area to volume ratio of cell
-Concentration gradient (or the solute concentration gradient)
-Nature of the material being exchanged
-temperature
Why is active transport called active transport?
This is because it involves expenditure or energy. Iron are continuously exchanged across membranes by active transport
Why is active transport called active transport?
This is because it involves expenditure or energy. Iron are continuously exchanged across membranes by active transport
What are some metabolic waste products?
Carbon dioxide
urea
What are the three differences between active transport and passive transport?
- Active transport requires energy whereas passive transport does not
- Active transport move substance from low to high concentration whereas passive does no
- Active transport will move substance that do not normally diffuse
What are two properties of cell membrane that determine why the membrane is selectively permeable? (Q6)
- They are made of phospholipid bilayer and tends to accept lipid-soluble molecules
- The channels or membrane proteins do not allow large molecules to pass through
What are two properties of cell membrane that determine why the membrane is selectively permeable? (Q6)
- They are made of phospholipid bilayer and tends to accept lipid-soluble molecules
- The channels or membrane proteins do not allow large molecules to pass through
What are two useful substances that are secreted from cells? (Q3)
Hormones- eg; insulin is involved in the control of blood sugar concentration
Mucus; used in the body defence by trapping pathogens
