1 and 2 please Flashcards
What are prokaryotic organisms?
They are just one prokaryotic cell ( single cellular) Eg. bacteria
What are Eukaryotic organisms?
Made up of many eukaryotic cells (multi cellular) Eg. plants and animals
Differences between a plant and animal cell?
Plant has all organelles in an animal cell plus: Cell wall with plasmodesmata Vacuole Chloroplasts
Description and function of plasma (cell surface) membrane?
Found on surface of animal cells, and inside cell wall of plant cells and prokaryotic cells. Made up mainly of lipids and protein Regulates movement of substances in and out of the cell Has receptor molecules that allow it to respond to chemicals like hormones
Description and function of cell wall?
Rigid structure that surrounds plant cells it’s mainly made of cellulose Supports plant cells
Description and function of the nucleus?
A large organelle surrounded by a nuclear envelope (double membrane) which contains many pores Contains chromatin (made up from DNA and proteins), and a structure called the nucleolus Controls the cells activities by controlling the transcription of DNA DNA contains instructions to make proteins The pores allow substances to move between the nucleus and the cytoplasum The nucleolus makes ribosomes
Description and function of lysosomes?
A round organelle surrounded by a membrane Contains digestive enzymes which are kept separate from the cytoplasm by the surrounding membrane Used to digest invading cells or to break down worn out components of the cell
Description and function of a ribosome?
Very small organelle which either floats free in the cytoplasm, or is attached to the rough endoplasmic reticulum Site where proteins are made
Description and function of Rough endoplasmic reticulum?
A system of membranes covered with ribosomes Folds and processes proteins which have been made at the ribosomes
Description and function of smooth endoplasmic reticulum?
Similar to RER except no ribosomes Synthesises and processes lipids
Description and function of a vesicle?
Small fluid filled sac in the cytoplasm surrounded by a membrane Transports substances in and out of the cell
Description and function of the golgi apparatus?
Fluid filled membrane bound flattened sacs Processes and packages new lipids and proteins Also makes lysosomes
Description and function of a mitochondrion?
Have a double membrane Inner one is folded to form cristae Inside is the matrix which contains enzmyes for respiration Site of aerobic respiration and where ATP is produced
Description and function of a choroplast?
Surrounded by a double membrane, and has membranes inside thylakoid membranes, which stack into grana Grana are linked together by lamellae Site of photosynthesis
Description and function of centrioles?
Small hollow cyclinders made of microtubules Involved in seperation of chromosomes
Description and function of Cilia?
Hair like substances found on the surface membrane of some animal cells Cross section has a ring of 9 pairs of protein microtubules inside with a pair in the middle aswell Allows movements of substances on the cell surface
Description and function of a flagellum?
Like Cilia except longer Propels cells
How are organelles involved in protein production?
Proteins are made at the ribosomes The Ribosomes on the rough endoplasmic reticulum make proteins that are excreted or attached to the cell membrane New proteins produced at the rough endoplasmic reticulum are folded and processed (sugar chains added) by the rough endoplasmic reticulum Then they are transported from the rough ER to the golgi apparatus in vesicles At the golgi apparatus the proteins undergo further processing Proteins enter more vesicles and are secreted out of the cell
What is the cytoskeleton of a cell?
Network of protein threads running through a cell, arranged as microfilaments (small solid strands) and microtubules (tiny protein cylinders)
4 Main functions of the cytoskeleton?
The microtubules and microfilaments support the cell’s organelles, keeping them in position. Helps strengthen the cell and maintain it’s shape Responsible for movement of materials within the cell, eg. chromosomes when they separate during cell division, relies on contraction of microtubules in the spindle Can cause the cell to move, eg in cillia or flagellum
How does a prokaryote’s cell size comapare to a eukaryote’ss cell size?
prokaryote’s cell size is very small (less than 2 um diameter Eukaryotes much larger, (10-100 um)
What’s the DNA like in a prokaryote’s cell compared to a eukrayotes cell?
prokaryote’s cell DNA is circular, whilst a eukaryotes is linear
Where is the DNA found in a prokaryote’s cell compared to a eukaryotes cell?
In a prokaryote’s cell there is no nucleus, so DNA is free in the cytoplasm Whereas in a eukaryote, nucleus is present so it’s found within the nucleus
What’s the cell wall in prokaryote’s cell like compared to a eukaryotes cell?
In a prokaryote’s cell it’s made of a polysaccharide, but not cellulose or chitin No cell wall in animal cells, cellulose in plants and chitin in fungi
How do the amount and type of organelles in a prokaryote’s cell compare to a eukaryotes cell?
In a prokaryote’s cell very few organelles and none are membrane bound In a eukaryotes cell, many membrane bound organelles present
How do the ribosomes differ in a prokaryote’s cell compared to a eukaryotes cell?
Small ribosomes in a prokaryote’s cell, and larger ribsomes in a eukaryotic cell
Structure of a bacterial cell?
Flagellum to propel cell DNA (bacterial chromosome) Plasmid (ring of DNA) Plasma membrane Cell wall Ribosomes
Magnification definition and formula?
How much bigger the image is than the specimen Magnification = image size / object size
Resolution definition?
How well a microscope can distinguish between 2 points that are really close to each other
How to convert between mm, um and nm?
mm = 1m x 10^-3 um= 1m x 10^-6 nm= 1m x 10^-9
Features of a light microscope?
Uses light Have lower resolution that electron microscopes (0.2um) Maximum magnification of a light microscope is x1500
Features of a scanning confocal microscope?
Use laser beams on a specimen tagged with fluorescent dye Laser causes dye to fluoresce, which is directed through a pinhole onto a detector connected to a computer which can produce a 3D image Pinhole creates a clearer image, as all out of focus light is blocked Can look at specimens at different depths
Features of a transmission electron microscope?
Uses electromagnets to focus a beam of electrons which is transmitted through the specimen, in which denser parts of the specimen absborb more electrons, which then appear darker in the image Only work on thin specimens Resolution of 0.0002 um Magnification of more than 1,000,000
Features of a scanning electron microscope?
Scans a beam of electrons across the specimen, knocking electrons off, which are collected in a cathode ray tube to form an image. Image can be 3D Resolution 0.002 um Magnification x 500,000
Using a light microscope, how do prevent the problem of the sample being transparent so the electrons pass straight through?
Can stain the sample, different parts take more up than others the contrast makes different parts show up
How do you stain samples for an electron microscope?
Objects are dipped into a solution of heavy metal, the metal ions scatter the electrons creating contrast again
How do you prepare a dry mount?
Use tweezers to put specimen on a slide, and put a cover slip on top
How do you prepare a wet mount?
Pipette a small drop of water onto the slide, use tweezers to put your specimen on top of water drop Put a cover slip on avoiding air bubbles Add a stain to one side of your specimen and put paper towel opposite side to draw it in
How do you find the value of each eye piece unit of an eyepiece graticule?
Use a stage micrometer, to measure what eyepiece unit is worth, need to re calibrate for different magnifications
Functions of water inside and outside of cells?
Water is a reactant in many important chemical reactions It’s a solvent, so allows biological reactions to take place in solution Water transports substances, liquid and a solvent so very useful can transport substances such as glucose and oxygen Helps temperature control as has a high specific heat capacity and high latent heat of evaporation It’s a habitat`
Why is water a polar molecule and what does this allow it to do?
Oxygen has a higher electronegativity than hydrogen, so attracts the electrons more making the oxygen delta negative, and the hydrogen’s delta positive Hydrogen bonding, as the delta positve hydrogen’s are attracted to the delta negative electrons of other water molecules
How can hydrogen bonding give water a high specific heat capacity?
Specific heat capacity is the energy required to raise the temperature of 1 gram of substance by 1 degree Hydrogen bonds between water molecules can absorb a lot of energy, meaning water requires a lot of energy to heat up Meaning it has a very stable temperature
How do hydrogen bonds give water a high latent heat of evaportation?
Hydrogen bonds mean that it takes a lot of energy to break the intermolecular forces between water molecules, so a lot of energy used up when water evaporates Good for cooling organisms, as when sweat evaporates it cools the surface of the skin
What’s cohesion and why are water molecules very cohesive and what does this help them do?
Is the attraction water molecules of the same type Occurs in water molecules as they are polar Helps them flow so they are good for transporting substances
How does water’s polarity make it a good solvent?
It can dissolve salts as the delta positively charged hydrogen’s will surround the negatively charged ions, and the delta negative oxygens will surround the positively charged ions, seperating out the salt causing it to dissolve
Why is water less dense when it is a solid?
Water molecules are held further apart in ice than they are in liquid, because each water molecule forms 4 hydrogen bonds to other water molecules making a lattice shape This is why ice floats
Why is ice floating useful to living organisms?
Ice acts as an insulating layer on top of the water, so the water bellow doesn’t freeze killing the living organisms
Most carbohydrates are polymers, what’s a polymer?
A molecule made up of many similar, smaller monomers bonded together
Structure of glucose?
It’s a hexose ( 6 carbon) monosaccharide Alpha glucose: starting at top right then going clockwise C1 bonded to CH2OH O C2 bonded to H above and OH bellow C3 bonded to H above and OH bellow C4 bonded to OH above and H bellow C6 OH bellow and H above Beta: the same as alpha, except on C2 OH is above, and H is bellow
How is glucose’s structure related to it’s function?
It’s the main energy source in animals as it’s structure makes it soluble, so can be transported easily, and it’s chemical bonds contain a lot of energy
What’s ribose?
Monosaccharide with five carbon atoms so it’s a pentose sugar Structure starting from Top of pentagon: O C1 OH above and H bellow C2 H above and OH bellow C3 H above and OH bellow C4 H bellow and CH2OH above
What elements do carbohydrates consist of?
Carbon Oxygen Hydroged
How do 2 monosaccharides bond together?
Via a condensation reaction A hydrogen atom from one monosaccharide binds to the OH group of another monosaccharide releasing a molecule of water, and forming a glycosidic bond (both molecules binded to each other by an oxygen) This a condensation reaction Forms a disaccharide
What’s the reverse of a condensation reaction?
A hydrolysis reaction, water is removed to split a molecule
What does the disaccharide maltose consist of?
2 molecules of alpha glucose binded to each other via a glycosidic bond
What does the disaccharide sucrose consist of?
When alpha glucose and fructose join together via a glycosidic bond
What does the disaccharide Lactose consist of?
When Beta glucose is bonded to galactose
What’s a polysaccharide?
When more than 2 monosaccharides join together
What do plants store excess glucose as?
Starch, when a plant needs energy breaks it down into glucose
What does starch consist of?
A mixture of the 2 polysaccharides of alpha glucose amylose and amylopectin
Describe the structure of amylose?
A long unbranched chain of alpha glucose. The angles of glycosidic bonds give it a coiled structure Condense structure makes it good for storage as can fit more into a smaller space
Describe the structure of amylopectin?
A long branched chain of alpha glucose, it’s side chains allow the enzymes that break down the molecule to get at the molecule to break the glycosidic bonds. So glucose can be released quickly
How do animal cells store glucose?
Store it as glycogen, another polysaccharide of glucose
Structure of glycogen?
Polysaccharide of alpha glucose, similar to amylopectin, except that it has far more side branches coming off it, so energy can be released more readily, which is good for animals
Why is it useful that starch is insoluble in water?
Means it doesn’t cause water to enter cells via osmosis, which would make them swell
Describe the structure and function of hydrogen bonds?
Long unbranched chains of beta glucose, the cellulose chains are linked by hydrogen bonds to form strong fibres called microfibrils The strong fibres provide strucutral support for the cell, eg. in plant walls
Explain the general structure of a triglyceride?
Glycerol bonded to 3 fatty acid chains Fatty acid chains are made of hydrocarbons (compounds that only contain hydrogen and carbon) The tails are hydrophobic, meaning the tails are insoluble in water
What elements do lipids contain?
Carbon, Oxygen and Hydrogen
How are triglycerides synthesised?
By the formation of an ester bond between each fatty acid and the glycerol molecule A condensation reaction occurs, between the OH group on the glycerol (prop-tri-ol) and the OH of the carboxylic group at the end of the hydrocarbon chain.
What’s the process of synthesising a triglyceride called?
Esterfication
What’s the type of reaction called which breaks down a triglyceride?
Hydrolysis
What’s a saturated fatty acid?
Hydrocarbon chain containing no double carbon carbon double bonds (saturated with hydrogen)
Functions of water inside and outside of cells?
Water is a reactant in many important chemical reactions It’s a solvent, so allows biological reactions to take place in solution Water transports substances, liquid and a solvent so very useful can transport substances such as glucose and oxygen Helps temperature control as has a high specific heat capacity and high latent heat of evaporation It’s a habitat`
Why is water a polar molecule and what does this allow it to do?
Oxygen has a higher electronegativity than hydrogen, so attracts the electrons more making the oxygen delta negative, and the hydrogen’s delta positive Hydrogen bonding, as the delta positve hydrogen’s are attracted to the delta negative electrons of other water molecules
How can hydrogen bonding give water a high specific heat capacity?
Specific heat capacity is the energy required to raise the temperature of 1 gram of substance by 1 degree Hydrogen bonds between water molecules can absorb a lot of energy, meaning water requires a lot of energy to heat up Meaning it has a very stable temperature
How do hydrogen bonds give water a high latent heat of evaportation?
Hydrogen bonds mean that it takes a lot of energy to break the intermolecular forces between water molecules, so a lot of energy used up when water evaporates Good for cooling organisms, as when sweat evaporates it cools the surface of the skin
What’s cohesion and why are water molecules very cohesive and what does this help them do?
Is the attraction water molecules of the same type Occurs in water molecules as they are polar Helps them flow so they are good for transporting substances
How does water’s polarity make it a good solvent?
It can dissolve salts as the delta positively charged hydrogen’s will surround the negatively charged ions, and the delta negative oxygens will surround the positively charged ions, seperating out the salt causing it to dissolve
Why is water less dense when it is a solid?
Water molecules are held further apart in ice than they are in liquid, because each water molecule forms 4 hydrogen bonds to other water molecules making a lattice shape This is why ice floats
Why is ice floating useful to living organisms?
Ice acts as an insulating layer on top of the water, so the water bellow doesn’t freeze killing the living organisms
Most carbohydrates are polymers, what’s a polymer?
A molecule made up of many similar, smaller monomers bonded together
Structure of glucose?
It’s a hexose ( 6 carbon) monosaccharide Alpha glucose: starting at top right then going clockwise C1 bonded to CH2OH O C2 bonded to H above and OH bellow C3 bonded to H above and OH bellow C4 bonded to OH above and H bellow C6 OH bellow and H above Beta: the same as alpha, except on C2 OH is above, and H is bellow
