Key Concepts Flashcards
What Is a Eukaryotic cell!?
contains a nucleus and other structures.
They are surrounded by membranes
What type of microscope can you see mitochondria with!?
A light microscope but not in detail
What type of microscope can you see ribosomes with!?
An electron Microscope
What is the function of CYTOPLASM in an animal cell!?
contain dissolved nutrients, salts and organelles.
Many chemical reactions occur here!!!!
What is the function of a NUCLEUS in plant and animal cells!?
Contains genetic material including DNA, which controls cell activity
What is the function a a cell membrane in plant and animal cells!?
Permeable to some substances
Controls the movement of substances which go in and out of the cell
What is the function of MITOCHONDRIA in plant and animal cells?
contain the enzyme for respiration
What is the function of RIBOSOMES in plant and animal cells!?
They are tiny structures and protein synthesis occurs here!
Are plant cells Eukaryotic or prokaryotic!?
Eukaryotic
What 4 structures do both plant and animal cells share!?
-a nucleus
-a cell membrane
-mitochondria
-ribosomes
What 8 structures do plant cells contain!?
Cytoplasm
A nucleus
Cell membrane
Mitochondria
Chloroplast
A cell wall
A permanent vacuole
Ribosomes
What do 8 structures do plant cells contain!?
A nucleus
A cell membrane
Chlorophyll
Mitochondria
Ribosomes
Chloroplast
Cell wall
Permanent vacuole
What is the function of CHLOROPLAST in a plant cell!?
contains the green pigment (chlorophyll) which absorbs the light energy.
Contains the enzymes needed for photosynthesis.
What is the function of CHLOROPHYLL in a plant cell!?
Green pigment that absorbs light energy
What is the function of THE CELL WALL in a plant cell!?
Provides structure and protection
Does an animal cell contain a cell wall!?
No
Does a bacterial cell contain a cell wall!?
Yes-not made form cellulose
What is the function of the PERMANENT VACUOLE in a plant cell!?
Is filled with cells that help to keep the cell’s shape.
Do animal cells contain a permanent vacuole!?
No- but they may contain one that is Small and temporary
Are bacterial cells Eukaryotic or Prokaryotic!?
Prokaryotic- they are single celled
What is a prokaryotic cell!?
does not contain a nucleus or any other structures
none are surrounded by membranes
Are bacterial cells visible underneath a microscope!?
Only larger bacteria are visible underneath a light microscope
HOWEVER……
Electron microscopes would be needed to see the cell in detail.
What structures do plant, animal and bacterial cells share!?
Cytoplasm
Cell membrane
What is the function of CHROMOSOMAL DNA in a bacterial cell!?
The same as DNA
not contained by a nucleus it is found loose in the cytoplasm
What is the function of PLASMID DNA in a bacterial cell!?
Are small, closed-circles of DNA that are present in the cytoplasm
They can move from one bacterial cell to another unlike CHROMOSOMAL DNA . This provides variation
What is the function of the FLAGELLA in a bacterial cell!?
They rotate OR move in a whip like motion to move the bacterium.
What is the word of one flagella!?
Flagellum
What is the function of the CELL WALL in a bacterial cell!?
Provides protection- isn’t made from cellulose
How do bacterial cells duplicate!?
They copy themselves by binary fission
What is binary fission!?
Very similar to mitosis but as the cell is PROKARYOTIC it is given a different name
How big is a EUKARYOTIC CELL!?
Between 5um-100um.
How big is a PROKARYOTIC cell!?
Between 0.2um-2.0um.
What are the outer layers of a EUKARYOTIC cell!?
Cell membrane which is surrounded by a cell wall ( cell wall=plants a fungi)
What are the outer layers of a PROKARYOTIC cell!?
A cell membrane surrounded by a cell wall
What structures does a EUKARYOTIC cell contain!?
Cytoplasm
Mitochondria
Chloroplast (plants)
Ribosomes
What structures do PROKARYOTIC cells contain!?
Cytoplasm
Ribosomes
NO….
mitochondria
Chloroplast
Where is the genetic material found in a EUKARYOTIC cell!?
-DNA found in the nucleus
- plasmids are found in a few eukaryotic organisms
Where is the genetic material found in a PROKARYOTIC cell!?
-DNA is is a single molecule:found free in the cytoplasm
- additional DNA found in plasmids
What is a plasmid!?
One or more rings of DNA
What type of cell division occurs in a EUKARYOTIC cell!?
Mitosis
What type of cell division occurs in a PROKARYOTIC cell!?
Binary fission
What is a specialised cell!?
Each cell is specialised to carry out a particular role to ensure the organism functions as a whole
-animals and plants therefore consist of many different types of cells working together
Name 2 examples of a specialised animal cell!?
Egg and sperm
Is a sperm cell HAPLOID or DIPLOID!?
Haploid
What is found in the HEAD of a sperm cell!?
Contains genetic material for fertilisation in HAPLOID nucleus
What is found in the ACROSOME of a sperm cell!?
Contains enzymes that sperm can penetrate egg
Where is the ACROSOME in a sperm cell found!?
In the head
What is found in the MIDDLE PIECE of a sperm cell!?
It is packed with mitochondria which are used to release energy needed to swim to and fertilise the egg
What is the use of the TAIL on a sperm cell!?
It enables the sperm to swim
Name a Fact about sperm cells……..
Sperm are the smallest cell in the human body and millions are made
What does an EGG cell contain!?
Cytoplasm
HAPLOID nucleus
Cell membrane
What is the job of the CYTOPLASM in an EGG cell!?
Contains nutrients for growth of the early embryo
What is the job of the HAPLOID nucleus in an EGG cell!?
Contains the genetic material for fertilisation
What is the job of the CELL MEMBRANE in an EGG cell!?
Changes after fertilisation by a single sperm so that no more sperm can enter
Fact about EGG cells……
Egg cells are one of the largest cells in the body and only a few are made
What are the job of the CILIA in a CILIATED EPITHELIAL CELL!?
Cilia are found on the surface and Beat to move fluids and particles up the trachea.
What are light microscopes used for!?
Used to study living cells and are for regular use when magnitude and resolution is relatively low
What are electron microscopes provide!?
Provide higher magnification and resolution images
Cannot used to see living cells
When was the first microscope discovered!?
It is unknown
What year was the compound microscope made in!?
1590s
Who invented the compound microscope!?
Dutch spectacle maker- Janssen
What was the compound microscope!?
Lenses in tubes
What is the magnification of the compound microscope thought to be!?
Between x3 and x9
How was he compound microscope used in the 1650s!?
It was used to observe and draw cells
Who used the compound microscope in the 1650s!?
Robert Hooke
Who created a microscope with a single spherical lens!?
Antonie Van Leeuwenhoek
What magnification did the single spherical lens microscope have!?
x275
What is the maximum magnification of a light microscope!?
x2000
What is the top magnification of a light microscopes when being used in schools!?
x400
What is the calculation for the MAGNIFICATION of a LIGHT microscope!?
Magnification of eyepiece x magnification of objective
What is the calculation for the magnification of an image when using a LIGHT microscope!?
Size of image
————————-
Real size of object
What is the only important factor to viewing cells!?
Magnification
Other than magnification what is another important factor when viewing cells with a light microscope!?
Resolution
What is the resolution!?
The detail that can be seen
The greater the detail in an image depends on what!?
Resolution or resolving power
What is the resolution of a light microscope!?
Around 2um OR 200nm
What does this resolution number mean!?
It Means it cannot distinguish points closer than 200nm
What does nm stand for!?
Nanometre
How much of a meter is a nanometre!?
1 billionth
How is one nanometre written as!?
1x10-9m or 1/1000 000 000
What does an election microscope use to see an image!?
Uses a beam of electrons instead of a ray of light.
What cannot be observed with an electron microscope!? And why!?
Living cells
because samples are placed into a vacuum
What are the 2 types of electron microscope!?
TEM: transmittion electron microscope
SEM: scanning electron microscope
What is a TEM microscope used to examine!?
Thin slices or sections of cells or tissues
How big is the depth of field in an SEM and what is it used for!?
Large depth of field
Used to examine the surface structure of specimens
What is the maximum magnification of a TEM!?
Around x1 000 000
What does this large magnification of a TEM mean!?
Images can be enlarged beyond that photographically
What is the limit resolution of an TEM!?
Less that 1nm
What does the 1nm resolution reveal!?
Structures that are not visible with a light microscope
What is the magnification of a SEM!?
Up to x30 000
What is the limit of resolution of an SEM microscope!?
Lower than a TEM at around 50nm
What are enzymes!?
Enzymes are proteins that function as biological catalysts
They are molecules that speed up a chemical reaction without being changed themselves
What shape are enzymes!? And what do they allow!?
Folded complex 3D shapes
allow smaller molecules to fit into them
What is the place where the molecules fit into the enzyme called!?
The active site
In the lock and key hypothesis what 2 shapes match together!?
The shape of the active site matches with the site of the substrate
What makes the enzyme highly specific!?
The active site shape and the substrate shape match together
How many types of reaction can an enzyme catalyse in!?
Usually one but some catalyse by a few types of reactions
What is the first step not the lock and key process!?
The substrate collides with the active site of the enzyme and becomes attached to the
What does the active site have to the substrate on the first step of lock and key!?
A complementary shape
What is the second step of the lock and key hypothesis!?
Enzyme catalyst breaks down the substrate
How can the fit between the enzyme and the substrate be described!?
As a perfect fit between the lock and key
What is the third step of the lock and key process!?
Products and still released from the active site
Describe the enzyme molecule at the end of the lock and key process…..
Unchanged meaning it can be reused
What 2 factors changes the shape of the active site!?
PH
Temp
What is a result of these factor changes!?
The substrate no longer fits into the enzyme resulting in the enzyme becoming denatured
Meaning the key won’t fit the lock
What is the calculation of the rate of an enzyme catalysed reaction!?
Rate of reaction= amount of substrate used OR the amount of product formed
————————————————————————————————
Time taken
What happens to the rate of an enzyme-catalyst reaction when temperature increases!?
It also increases
What happens to the rate of an enzyme-catalysed reaction at high temperatures!?
It decreases as enzyme becomes denatures and can not longer function.
As the temperature increase what also increases!? (Enzymes)
The rate of enzyme activity
When is the OPTIMUM activity reached!?
At the enzyme’s optimum temperature
A continued increase in temperature results in what!? (Enzymes)
A sharp decrease in activity as the enzyme’s active site changes shape and becomes denatured
What does a change in pH alter in enzymes!?
The shape of the enzymes active site
What does the optimum ph depend on for each enzyme!?
It depends on where the enzyme usually works
Name 2 examples of an enzyme and there ph
Small intestine: pH of around 7.5
Stomach: pH of around 2
As pH increases what also increases!?
Enzyme activity
As optimum activity is reached what other optimum is reached in terms of Ph
Enzymes optimum Ph is also reached
If a continued increase of pH occurs what will happen to the enzymes activity!?
A sharp decrease in activity and active site will change shape resulting the enzyme becoming denatured
Enzymes will work best if…….
There is a high substrate concentration
As the substrate concentration increases what also increases!?
Enzyme activity
Why will the rate of enzyme activity not last forever!?
Because a point will be reached when the enzyme becomes saturated and no more substrates can fit at any one time even though there is plenty of substrate available
What is reached at the enzyme’s optimum substrate concentration!?
An optimum rate
What does a continued increase in substrate concentration result in!?
The same amount of activity as there a not enough enzyme molecules available to break down the excess substrate molecules
What is food made out of!?
Large insoluble molecules
Name the 3 large molecules needed for growth, repair and metabolism
Carbohydrates
Proteins
Lipids
Name the 3 things carbohydrates, proteins and lipids are used for……
Growth
Repair
Metabolism
Where are carbohydrates, proteins and lipids found!?
In food
Why are digestive enzymes needed to break down c,p,l!?
Because the molecules are to large to pass from the intestine to the blood
Name 4 examples of a carbohydrate
Glycogen
Starch
Sucrose
Glucose
What is the building block of a carbohydrate!?
A monosaccharide
What is a monosaccharide!?
A simple sugar such as glucose and a fructose
Enzymes join monosaccharides together to for what!?
Disaccharides (2 monosaccharides) and polysaccharides (long chains or monosaccharides)
What enzymes break down disaccharides and polysaccharides!?
Carbohydrase enzymes
What are disaccharides and polysaccharides broken down into!?
Monosaccharides (simple sugars)
Where is the carbohydrase enzyme produced!?
In you mouth (saliva)
Pancreas
Small intestine
What are proteins!?
They are large molecules from amino acids joined together to form chains
What enzymes do proteins include!?
Haemoglobin
Collagen
Keratin
What does each protein contain!?
Hundreds or even thousands of amino acids joined together in a unique sequence which are folded into the correct shape
Which gives each protein it’s own individual properties
Protease is responsible for what!?
Breaking down proteins in our food into amino acids
How are new proteins formed!?
By different enzymes joining amino acids together which are needed for growth and repair
Where are protease enzymes produced!?
Stomach
Pancreas
Small intestine
What are lipids!?
They are fats and oils
What are lipids made from!?
They are large molecules made from smaller units of fatty acids and glycerol
What breaks down lipids!? And how does it do it!?
Lipase
Breaks down lipids in the diet into fatty acids and glycerol
Where is lipase produced!?
Pancreas
Small intestine
What are all 3 enzymes also used for!?
Absorbing nutrients that we need from food in an exchange system. It does this by have a large surface area
Where does digestion start!?
In your mouth
What is the name of the organ that releases saliva!?
Salivary gland
What enzyme does saliva contain!?
Amylase
What is amylase used for in digestion!?
Helps break down carbohydrates
What type of digestion occurs in the mouth!?
Chemical digestion
What happens after our food is placed into our mouths!?
We bite our food with our teeth
What does biting our food do to benefit digestion!?
Breaks down food into smaller pieces making it easier to swallow and it increases the surface area of food!
What type of digestion is chewing!?
mechanical digestion
What do chemical and mechanical digestion help with!?
Helps to move things along
What is the 3rd step of digestion!?
After swallowing your food it travels down the oesophagus to the stomach
What is the function of the oesophagus!?
Carries food from mouth to stomach
Describe the stomach……
The stomach is a big,hollow, j-shaped organ, that’s got lots parts to break down food
Describe the stomach wall…..
A strong muscular stomach that churns food
Is the churning of food a chemical or mechanical digestion!?
Mechanical
What enzyme does the stomach contain!?
Protease which breaks down proteins
This is chemical digestion
What does the stomach also contain!? And what is it used for!?
Hydrochloric acid which is a strong acid and it is used to kill bacteria in food and lowers the pH of the environment which helps protease enzymes to work
This is chemical digestion
What is the 4th stage of digestion!?
Food is passed through the small and large intestines
What are the 2 sections of the small intestines called!?
The duodenum and the ileum
Which part of the small intestine does food travel through first!?
The duodenum
what happens in the duodenum during digestion!?
Lipids are digested and even some proteins and carbohydrates are digested here too!
What occurs in the ileum during digestion!?
All the pieces of food are finally absorbed by the blood stream and taken to the rest of the body for energy, growth and repair
What does the ileum contain!? And what do they do!?
Villi which increase surface area which allows a lot of absorption
There are 3 adaptations of villi list the first one…….
The surface layer of the villus is only one cell thick meaning there is only a thin wall for food to travel through
What is the 2nd adaptation of villi!?
They have a good blood supply from a network of blood vessels that helps carry absorbed food away from the
What is the 3rd adaptation of villi!?
Each villus is covered in there own little villi called microvilli
What is the 5th process of digestion!?
Your liver,pancreas and gall bladder then help out.
What does the liver contain!?
Bile
Where is bile stored!?
It is stored in the gall bladder and is then squirted into the small intestine
What is bile used for!?
Used to neutralise the acidity in foods so that the digestive enzymes made in the pancreas can work this all occurs in the stomach
What does bile also help with!?
Fat digestion. It makes the large fat globules smaller so that increases surface area for the enzymes to work on!
What is the 6th process of digestion!?
Everything left in the small intestine carries on to the large intestine where water is absorbed and a process called egestion begins
What is egestion!?
Taking food in
What is the 7th process of digestion!?
Undigested food leaves the body as faecal matter through the rectum to the anus
How do particles in a solid and a gas move!?
More continuously meaning that particles will spread themselves evenly throughout a liquid or gas
Define the process diffusion……
If particles of a substance are in a higher concentration they will start to move from this region to where they are in a lower concentration
What direction do particles move in during diffusion!?
They move in both directions BUT there will be a NET movement from a high to low concentration they will end up evenly spread throughout the liquid or gas but will continue to move!
If a crystal of a coloured chemical is placed in water what will happen!?
The particles will diffuse and mix with the water particles creating an evenly concentrated solution
State the steps of diffusion
- Coloured crystal is dissolved
- They mix through diffusion moving from high- low creating and evenly concentrated solution
What is the word given to the crystal in this experiment!?
It is the solute
As it is being dissolved
What is the word given to the water in this experiment!?
The water is the solvent
It dissolves the crystal
Describe how the particles have moved during this experiment!? (Crystal and water)
The particles have moved from a HIGH concentration in the crystal to a LOW concentration in the water
Describe a concentration gradient…..
The difference in concentration
What causes the particles when they move DOWN a concentration gradient!?
A high concentration to a low concentration
How else can diffusion occur!?
Across a membranes between the outside and the inside of cells
How does a concentration gradient affect the rate of diffusion!?
The greater the difference in concentration the quicker the rate of diffusion
How does temperature affect the rate of diffusion!?
The higher the temperature the more kinetic energy the particles will have so they will move and mix and a faster rate
How does surface area of the cell membrane separating different regions affect the rate of diffusion!?
The greater the surface area the faster the rate of diffusion
What is the name of the law that diffusion is calculated by!?
Fick’s law
What is the calculation for diffusion!?
Rate of diffusion = surface area x concentration difference
——————————————————————-
Thickness of membrane
How do substances diffuse in a single celled organism!? And what size will the substance need to be!?
In and out of the cell across its surface
Because of cell size substances will need to diffuse 1um OR less to where they are needed
Explain how diffusion occurs multicellular organisms………. And name and example
1.Substances diffuse into the leaves and simple roots over their surface
2.Once inside the plant they don’t need to move far!
3.substances move into and around the plant by diffusion and osmosis
Eg: plants and moss
Explain how diffusion occurs in simple organisms…….
1.They take in the substances over their body surface
2. Their needs are determined by their volume
3.all organisms at the same rate as their volume!!!!
What is osmosis!?
The movement of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration.
What is osmosis in terms of concentration!?
Osmosis is the diffusion of water molecules from a region of higher concentration to a region where they are in lower concentration through a partially permeable membrane
Does a dilute solution contain a high or low concentration of what’re molecules!?
High concentration of water molecules
Does a concentrated solution contain a high or low concentration of water molecules!?
Low concentration
What happens when the concentration of water is the same on both sides of the membrane!?
The movement of water molecules will be the same in both directions. There will be no NET movement of water molecules
What happens with solutions containing different solutes in terms of osmosis!?
Similar observations will be made with solutions containing different solutes as what happened with a membrane
What dilute solutions do cells contain!?
Dilute solutions of ions,sugars and amino acids
What is an amino acid!?
The building blocks that make up a protein molecule.
Describe the cell membrane of a living cell and how that affects osmosis….
The cell membrane is particularly permeable so water will move into and out of the cell by osmosis
What is a root hair cell!?
A specialised cell that increases the surface area of the root epidermis to improve the uptake of water and minerals.
Explain how an isolated plant cell placed in a dilute solution or water will take in water……
- Water will be taken in by osmosis
2.if the soil is wet or moist then root hair cells will take up water by osmosis
Explain how leaf cells of land plants do in terms of osmosis…..
Unless it is raining or humidity is high they have a tendency to lose water
What is humidity!?
The amount of water vapour in the atmosphere measured as a percentage.
What do plant cells contain outside the cell membrane!.
They have strong cellulose cell wall
What is a cell membrane!?
A selectively permeable membrane surrounding the cell and controlling the entry and exit of materials.
What is a cellulose!?
A carbohydrate. It forms the cell wall in plant cells
Describe the cell wall……
The cell wall is fully permeable to all molecules. It supports the cell and stops it bursting when it gains water by osmosis
Under normal circumstances cells in all organisms live in a safe equilibrium. Why is this!?
They have enough water to live but not too much. They also have the correct amount of salts and sugars
What happens when we place a cell into pure water!?
In pure water, the cell contents push against the cell wall and the cell becomes turgid.
What is a turgid!?
Enlarged and swollen with water. Having turgor. Description of a plant cell in which the vacuole has swollen due to water gain by osmosis.
What is the role of a fully turgid cell!?
Fully turgid cells support the stems of non-woody plants.
What happens when you place a cell in a more concentration solution!?
The cell membrance starts to pull away from the cell wall. The cell becomes flaccid.
What is a flaccid!?
Soft and floppy.
What happens when you put a cell into a highly concentrated solution!?
In a very concentrated solution, the cell membrane pulls away from the cell wall completely; this is plasmolysis.
What happens to animal cells when they take in water by osmosis!?
Animal cells also take in and lose water by osmosis. They do not have a cell wall, so will change size and shape when put into solutions that are at a different concentration to the cell contents.
What will happen to red blood cells in a concentrated solution!?
Red blood cells lose water and shrink in a concentrated solution.
What happens to red blood cells if a solution is too dilute!?
They swell and burst in a solution that is too dilute.
In an animal cell , what fluid’s concentration must be kept between strict limits !?
In animals, the concentration of body fluids, blood plasma and tissue fluid must be kept within strict limits.
What happens if an animal cell loses or gains too much water!?
If cells lose or gain too much water by osmosis, they do not function efficiently.
What is the equation for water uptake in 1 hour!?
Change in mass x 60mins/
length of experiment in minutes
What is the equation for change in mass!?
Mass at end - mass at start/ mass at start x 100
What is blood plasma!?
The liquid part of the blood containing useful things like glucose, amino acids, minerals, vitamins (nutrients) and hormones, as well as waste materials such as urea.
What is tissue fluid!?
Fluid which is derived from blood plasma that passes through the walls of capillaries.
How are substances moved down concentration gradients!?
Substances are transported passively down concentration gradients
What is it meant by the term transported passively!?
This is the movement of molecules down a concentration gradient without the need for additional energy, eg diffusion and osmosis.
How are substances often moved in terms of concentration!?
Often, substances have to be moved from a low to a high concentration against a concentration gradient.
What is active transport!?
The transport of molecules against their concentration gradient from a region of low concentration to a region of high concentration. The process requires energy
How does active transport allow plants to take up the nutrients they need from the soil around it!.
For plants to take up mineral ions, ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil
How are nitrates moved through the root hair cells!?
Nitrates are moved by the process of active transport from a low concentration in the soil to a higher concentration in the plant
How is glucose molecules moved in animals!?
In animals, glucose molecules have to be moved across the gut wall into the blood.
The glucose molecules in the intestine might be in a higher concentration than in the intestinal cells and blood – for instance, after a sugary meal. What does this mean!?
At this point it will diffuse from high concentration in the intestine to a lower concentration in the blood. This doesn’t require energy.
there will be times when glucose concentration in the intestine might be lower. Meaning that!?
movement of glucose involves active transport. The process requires energy produced by respiration.
What is aerobic respiration!?
Respiration that requires oxygen.
What substances are transported by diffusion!?
Carbon dioxide, oxygen, water, food substances, wastes, eg urea
Is energy required in diffusion!?
No
What substances are transported by osmosis!?
Water
Is energy required for osmosis!?
No
What substances are transported by active transport!?
Mineral ions into plant roots. Glucose from the gut into intestinal cells, from where it moves into the blood
Is energy required for active transport!?
Yes
What is the cell wall made from?
cellulose
How many flagella’s does a bacterial cell posses?
A bacterial cell can possess more than one flagella
