Chemistry of Life Flashcards
What is an Acid?
A compound that released H+ ions into solution. pH < 7
What is a Base?
A compound that takes up H+ ions into solution. pH > 7
What is a buffer?
A solution that resists change in pH. Usually a combination of a weak acid and one its soluble salts
What is the pH of blood?
Between 7.35 - 7.45
What is the formula for carbohydrates?
Cx(H2O)y
What does dissociation mean?
Separates into constituent ions
99% of all living matter consists of which four atoms?
Nitrogen, hydrogen, carbon, oxygen
How many elements make up the cell?
16
Which elements make up lipids?
Carbon, Hydrogen, Oxygen
HCl is an example of an acid or a base?
Acid
How is HCl dissociated in solution?
H+ and Cl-
Positively charged ion is
Cation
Cation is…
a positively charged ion
Negatively charged ion is
Anion
Anion is…
Negatively charged ion
Forumla for pH
-log10 (H+ concentration)
Sodium hydroxide formula
NaOH
Sodium hydroxide dissociates into
Na+ and OH-
Ethnic acid formula
C3H3COOH
How does ethanoic acid dissociate in water?
C2H5COO- and H+
How is blood buffered?
Phosphate ions, hydrogen carbonate, blood proteins
Why is it important to use buffers in laboratory experiments?
To keep the pH of a solution under control when diluting or adding acids or bases.
Metabolism is…
All the chemical reactions that occur within an organism
The role of (nitrate) NO3- in plant metabolism is…
Required for DNA, RNA and protein synthesis
The role of calcium (Ca2+) in plant metabolism is…
Used to synthesize calcium pectate
What is calcium pectate?
Forms the lamella, a layer between the walls of adjacent plant cells
The role of magnesium (Mg2+) in plant metabolism
Used in chlorophyll production
The role of phosphate (PO4 3-) in plant metabolism
For energy in the synthesis of ATP from ADP, and in DNA and RNA replication/transcription.
A human cells consists of **% water
80%
What type of bond does water use?
Covalent
Charge of a H2O molecule
Neutral
Which atom(s) in H2O are electro negative?
Oxygen
Which atom(s) in H2O are electro positive?
Hydrogen
Why is Oxygen electro-negative in H2O?
Because the large nuclei of oxygen pulls the electrons away from the small nuclei of hydrogen
Why is hydrogen electro-positive in H2O?
Because the large nuclei of oxygen pulls the electrons away from the small nuclei of hydrogen, therefore giving oxygen additional elections and hydrogen fewer
What is a polar molecule?
The unequal distribution of electrical charge across a molecule
What is a polar molecule?
The unequal distribution of electrical charge across a molecule
How are water molecules bound?
Hydrogen bonds
What is a covalent bond?
A bond between two atoms in which electrons are shared between them.
What is a hydrogen bond?
A link between two polar molecules which combines using the weak positive of one and weak negative charge of the other to form a bond.
How strong is a covalent bond?
Kinda strong, but not the strongest
How strong is a hydrogen bond?
Weak
What is cohesion?
The force that attracts hydrogen bonds between polar molecules or other charged surfaces together
What kind of molecule is water?
Polar
Name some examples of solutes that water is a good solvent for:
- ionic substances i.e. sodium chloride (NaCl-)
2. Organic molecules with ionized groups (COO-, NH3+)
NaCl- is added to water. Which is the solvent and which is the solute?
Solvent = NaCl- Solute = water
A polar molecule that can dissolve in water is known as
Hydrophilic
Are non-polar molecules hydrophilic or hydrophobic?
Hydrophobic
What does hydrophilic mean?
Dissolves in water
What does hydrophobic mean?
Does not dissolve in water
Give an example of a hydrophobic substance
Oil
Give an example of a hydrophilic substance
NaCl-
What does the term “Specific Heat Capacity” mean?
The heat needed to break bonds
What is the specific heat capacity of water?
4.184 kj / kg /^celcius.
This means that it takes 1.184 kj of heat to increase the temperature of 1kg of water by 1 degree Celsius
Why is the specific heat capacity important for humans?
Because it means humans can tolerate large fluctuations in environmental temperature without changing internal temperature.
What is the force by which charged molecules stick together?
Cohesion
Are ionic substances hydrophilic or hydrophobic?
hydrophilic
Are alcohols and sugars hydrophilic or hydrophobic?
hydrophilic
Are oils hydrophilic or hydrophobic?
hydrophobic
Are oils polar or non-polar molecules?
non-polar?
The term used to describe the heat needed to break bonds
The specific heat capacity
A link between two polar molecules which combines using the weak positive of one and weak negative charge of the other to form a bond.
Hydrogen bond
A bond between two atoms in which electrons are shared between them.
Covalent bond
4.184 kj / kg /^celcius is…
The specific heat capacity for water
The intramolecular bonds in water
covalent
The intermolecular bonds in water
hydrogen
Surface tension is..
The cohesion of water at the water-air interface. Occurs because more molecules of H2O are present here.
Is water compressible?
No
Is water incompressible?
Yes
What does it mean if water is incompressible?
The distance between molecules is very small and can therefore not be shortened (or, compressed)
Maximum density of Water is at what temperature?
4^C
Is H2O-ice more or less dense than liquid water?
less
Why does it mean that ice floats on water?
Because ice is less dense than water
Water is at its maximum density at 4^C, what is a consequence of this to living organisms?
In rivers and lakes, the floating layer of ice insulates the large mass of water so that it can’t freeze solid. Therefore the aquatic life in such spaces can survive.
What shape does the water molecule take? (almost)
Tetrahedron
What symptoms would be shown by a plant grown in magnesium deficient soil?
Lack of chlorophyll production
In plants, what is chlorophyll?
Great pigment found in the chloroplasts of cells. It is essential in photosynthesis and allowing plants to absorb energy from plants
What are 5 properties of water that make it essential for life?
1.
What is xylem tissue?
One of two types of transport tissue in vascular plants
Phloem is?
One of two types of transport tissue in vascular plants
Why can a pond skater walk on water but humans can’t
because the surface tension of the water is strong enough to hold the tiny weight of the pond skater, and because this weight is distributed across a large diameter relative to its size and weight.
Carbon is the — most abundant element in cells and living organisms
Third
What is the third most abundant element in cells and living organisms
carbon
What is an organic compound?
A large carbon compound which carbons are covalently linked to each other and to hydrogen molecule
What bonds are used between carbons are organic compounds?
covalent
Organic compounds are made up (mostly) from which two elements?
Carbon and Hydrogen
Properties of carbon
- Can form four strong, stable, covalent bonds (four lone pairs of electrons)
- Carbon atoms can react with one another ro form extended chains, or skeletons
- Can form covalent bonds with other atoms too, e.g. oxygen, nitrogen, hydrogen and sulfur.
How many covalent bonds does carbon form? And why?
Four, because it has four lone pairs
What shape does methane form?
Tetrahedron.
What are the four families of organic molecules?
Lipid, nucleic acid, carbohydrate, protein
Examples of carbohydrates
sugars, starch, glycogen, cellulose
Types of carbohydrate
Monosaccharide, disaccharide, polysaccharide
Features of a monosaccharide
Smalll molecules, soluble in water and sweet in taste Simple sugars e.g. 1. trioses (C3-H6-O3) 2. Pentoses (C5-H10-O5) 3. Hexoses (C6-H12-O6) *Numbers should be sub-script
What is the formula for a Triose?
C3-H6-O3
*Numbers should be sub-script
What is the formula for Pentoses?
C5-H10-O5
*Numbers should be sub-script
What is the formula for hexoses?
C6-H12-O6
*Numbers should be sub-script
Triose, pentose and hexose are all types of what?
Monosaccharide
C3-H6-O3 is the formula for…
*Numbers should be sub-script
Triose - monosaccharide
C5-H10-O5 is the formula for…
*Numbers should be sub-script
Pentose - monosaccharide
C6-H12-O6 is the formula for…
*Numbers should be sub-script
hexose - monosaccharide
Features of a disaccharide…
Two simples sugars chemically linked by a glycosidic bond during a condensation reaction e.g.
Sucrose = glucose + fructose
lactose = glucose + galactose
Maltose = glucose + glucose
Sucrose =
glucose + fructose
glucose + fructose =
Sucrose
lactose =
glucose + galactose
glucose + galactose =
lactose
Maltose =
glucose + glucose
glucose + glucose =
Maltose
Features of polysaccharides
Lots of simple sugars in a chain chemically linked by glycosidic bonds, e.g.
Starch (Fuel storage in plants)
Glycogen (energy storage in animals)
Cellulose (major component of plant cell walls)
Importance of monosaccharides
All green leaves produce glucose using light and glucose is important in respiration
Glucose is which type of monosaccharide?
Hexose (C5-H10-O5)
What is the chemical formula for glucose?
C6-H12-O6
What shape does glucose take?
Cyclic
How many carbons does glucose have?
6 (hexose)
What is an isomer?
Molecules that have the same molecular formula but different structural formula
What is the molecular formula?
Shows the name and number of atoms in a molecule
What is the structural formula?
shows the way atoms are arranged in the molecule
Alph-glucose and beta-glucose differ by…
The positions of the H and the OH bound to the carbon-1.
In solution, glucose transitions between both structures
What is Benedict’s test?
When heated with Benedicts solution, the COOH group from the sugar reduces Cu2+ ions of copper(II) sulfate to Cu+ ions, which then form a brick-red precipitate of copper(I) oxide. In this process, the aldehyde group is oxidized to a carbonyl group (C=O).
If no reducing sugar is present the solution remains blue after heating.
The greater the sugar content, the bigger the color change.
blue -> green -> yellow –> brown -> red
What is Benedict’s solution?
An alkaline solution of copper(II) sulfate
What color is the solution in Benedicts test if there is no reducing sugar present?
Blue
What is the color sequence in Benedicts test if there is reducing sugar present?
blue -> green -> yellow –> brown -> red
blue -> green -> yellow –> brown -> red
is the sequence for which test? And what does it measure?
Benedicts test.
Measures the concentration of reducing sugar in a solution
Examples of hexose sugars
Glucose, fructose and galactose
Glucose, fructose and galactose are examples of what type of monosaccharide?
hexose
Ribose is what type of monosaccharide?
pentose. C5
Glyceraldehyde is what type of monosaccharide?
triose
What is the purpose of glyceraldehyde?
An intermediate in respiration and photosynthesis
What is the purpose of ribose
basic building block of RNA, ATP, NAD and NADP
Where would you find deoxyribose?
DNA
Where would you find deoxyribose?
DNA
What is the byproduct of the formation of disaccharides?
H2O
When two monosaccharides come together to form a disaccharide, what reaction occurs between the two macromolecules?
condensation
Because a H2O is produced
The bond between two monosaccharides in a disaccharide is known as a…
glycosidic bond
How strong is the glycosidic bond?
Strong
What type of bond is a glycosidic bond?
Covalent
Breaking up of a disaccharide in to two monosaccharides is called a….. reaction
hydrolysis
What is a hydrolysis reaction
A reaction that requires H2O
Polysaccharides comprise of how many types of monosaccharide
One
What is a condensation reaction?
A reaction which binds two molecules, producing H2O as a byproduct
What is a polymer
A long chain of Monomers
Starch is a mixture of which two types of polymer?
Amylose and amylopectin
Amylose is…
an unbranched chain of alpha-glucose resides
Amylopectin is…
branched chains of alpha-glucose
What is the function of starch?
storage of carbohydrate in most plant species.It is useful because it takes up little space (compact and insoluble) and are readily hydrolyses to form sugar when required.
The starch in processed food is different too that found in plants by…
The starch chains have been broken down, making it easier for the consumer to digest.
Storage of carbohydrate in most plant species.It is useful because it takes up little space (compact and insoluble) and are readily hydrolyses to form sugar when required.
Starch
branched chains of alpha-glucose
Amylopectin
an unbranched chain of alpha-glucose resides
Amylose
Amylose and Amylopectin are types of what?
Starch
A reaction which binds to molecules producing H2O as a byproduct
Condensation reaction
A reaction which separates two molecules, requires H2O for completion
Hydrolysis reaction
How do you test for the presence of starch?
Add a solution of iodine in potassium iodide, if it turns blue-black color starch is present.
The iodine molecules fit in to the centre of the starch helix
Add a solution of iodine in potassium iodide is a test for what?
Starch
Glycogen is..
A polymer of glucose
A polymer of glucose is called
Glycogen
Difference between glycogen and amylopectin
They are similar but glycogen is larger and more highly branched
Where are you likely to see granules of glycogen in the human body?
Via an electron microscope: liver cells and muscle fibers
Though glycogen stores are found throughout the body except the brain
What organ would you not find carbohydrate stores in?
Brain
Similar to glycogen, but glycogen is larger and more highly branched
amylopectin
Similar to amylopectin, but larger and more highly branched
Glycogen
During exercise, what does the body use up first? Glycogen stores or fat?
Glycogen
Roughly how many polymers od beta-glucose would you find in a chain of celluose?
2000-3000
Alpha-glucose… Where are the carbon-1 -H and -OH groups positioned?
-H is on top and -OH is on the bottom
beta-glucose… Where are the carbon-1 -H and -OH groups positioned?
-OH is on top and -H is on the bottom
-OH is on top and -H is on the bottom… Which type of glucose am I?
beta-glucose
-H is on top and -OH is on the bottom, which type of glucose am I?
Alpha-glucose
How do beta-glucose chains form?
The adjacent molecules are upside down to one another
Cellulose is comprised of which type of glucose?
beta-glucose
What kind of structure does cellulose form
long, straight chains
What bonds hold the cellulose chains together?
hydrogen bonds
Cellulose is found in the plant cell wall, how is it suited for a strong cell boundary?
Bonds between beta-glucose molecules
Hydrogen bonds between and within the chains of beta-glucose
The various beta-glucose fibers are arranged in difference directions
What is the difference between molecular formula and structural formula
Molecular formula doesn’t display the arrangement of the atoms. You can have many isomers with the same molecular formula but not the same structural formula
alpha-glucose and beta-glucose are isomers, what does this mean?
They have the same molecular formula but different structural formulas.
What is in an iodine solution?
Iodine and potassium iodide
How do you test for the presence of starch?
with an iodine solution
What are the color changes that occur with a starch test?
If no starch is present the solution won’t change colour
If starch is present, a blue/black/purple solution is produced
What is a reducing sugar?
A sugar that can carry out a chemical reaction (reduction) which involves giving electrons to another substance.
Which is the only sugar which will not give a positive result in the Benedict’s test?
Sucrose.
why? Because it is not a reducing sugar.
What reaction forms between the glycerol and fatty acid during the production of Triglycerides? And what type of bonds are formed?
Condensation reaction
Ester bonds
What molecules make up a triglyceride?
Glycerol and three fatty acids
Fatty acids are:
Long hydrocarbon chains between 14 and 22 C atoms long.
Molecular formula for glycerol
C3H5(OH)3
*numbers are subscript
Two main class of lipid
- Triglyceride
2. phospholipids
What is an Acid?
A compound that released H+ ions when dissolved in water.
What is the difference between a strong acid and a weak acid?
Strong acids completely dissociate in solution, i.e. complete loss of H+. Weak acids only partially dissociate.
Organic molecules that are acids are… weak or strong acids?
Weak.
What is a base?
A compound that reacts with the free H+ ions, removing them from the solution to neutralize it. Bases that soluble in water are alkalis
pH > 7 is
Alkali
pH < 7
Acid
pH of acid (A)
A < 7
pH of Alkali (Al)
Al > 7
pH represents the concentration of…
H+ ions in solution
What is an indicator
A compound that changes color in solutions of different pHs.
Universal indicator changes to which color at pH 7?
Green
Universal indicator changes to which color at pH 14
Blue/violet
Universal indicator changes to which color at pH 1
Red
What is a buffer?
A compound that resists changes to pH when an acid or alkali are added to the solution.
How does a buffer work?
It binds to H+ ions when they are present in solution (i.e. adic added) and loses H+ ions when they are absorbed (i.e. alkali added).
Triglyceride ester bonds use which groups?
-OH of the carboxylate group of the fatty acid and one of the OH groups of the glycerol
What groups comprise a fatty acid molecule?
Carboxyl group and hydrocarbon chain
A molecule with a carboxyl group and a hydrocarbon chain (14-22 C atoms in length) would be…
Triglyceride
What does saturated and unsaturated fatty acid mean?
Saturated fatty acids only have single bonds in their tailsand therefore no more hydrogen can be added to the chain. Unsaturated fatty acids have one or more double bonds in the C chain and therefore additional hydrogen can be added.
If there is only one double bond the molecule is called a monounsaturated fatty acid. If the molecule has more than one double bond it is a polyunsaturated fatty acid
Polyunsaturaated fatty acids have a higher or lower melting temperature?
Lower. Think of Margarine.
Why is a triglyceride insoluble in water?
Because the large fatty acid chains are non-polar
Does a triglyceride contain more or less energy than carbohydrate? Why?
More energy because (1) there is less oxygen in a triglyceride than a carb of the same size/mass. (2) the molecules are packed closer together therefore more molecules per size/mass of glycogen or starch.
What properties of triglycerides make them idea for energy storage in humans?
- hydrophobic and insoluble in water
- hydrocarbon tails are chemically unreactive
- lack of O2 and increased energy storage
Why are triglycerides better energy storage molecules than glycogen?
more energy can be stored per mass therefore more energy and less weight to carry.
What are the uses of triglycerides in animals?
- Energy storage
- Insulation
- Waterproofing
Where is glycogen mainly stored?
Liver and muscles
Why are triglycerides important in plants?
Generally found ion seeds, the seeds need to disperse further from the mother plant so the seeds need to store energy and be light.
Do plants get most of their energy storage from starch or lipids?
lipids - triglycerides
Are liquid or solid triglycerides easier to break down?
Liquid.
The more C=C bonds, the higher or lower the melting temperature?
Lower
Are you more likely to find saturated or unsaturated fats ion animals?
Saturated fats
Are you more likely to find saturated or unsaturated fats in plants?
Unsaturated
Are phospholipids hydrophilic or hydrophobic?
Both.
What reaction joins two amino acids together?
Condensation
What are the four groups attached the the central carbon in an amino acid
- A single hydrogen
- A carboxyl group
- Amino group
- R group
Name the two functional groups of amino acids
carboxyl and amino groups
Molecular formula for amino acids
NH2-CHR-COOH
Amino acids can ionise and both acids and bases, True or false?
True
What is a Zwitterion
an ion with both positive and negative charges
Whaat bond forms between two amino acids?
Peptide bond
What type of bond is a peptide bond?
Covalent
The primary structure of the protein is
amino acid sequence
The secondary structure of the protein is
the folded protein with a-helices and b-sheets.
a-helices and b-sheet are bonded together with which type of bond?
hydrogen bonds of the backbone
Tertiary structure
Formed by bonds of the side chain
Tertiary structure
Formed by bonds of the side chain
What types of bonds are used in bonding side chains of amino acids?
Disulfide bonds - between cysteine residues
ionic bonds - between charged side chains
Hydrogen bonds - between O and/or N with a delta- charge and a hydrogen with a delta+ charge.
Van der Waal bonds - forms between polar side chains
Disulfide bonds
Forms in amino acids between cysteine residues
very strong, difficult to break
Organisms which live in extreme environments have a lot of them
What’s the difference between fibrous and globular proteins?
Fibrous are long chains like collagen
Globular form tertiary ball-like structures
Quaternary structure
When a protein has many components, when all the parts of the complex come together to form the complex, this is the quaternary structure. i.e. collagen.
A hemoglobin molecule consists of…
four poly peptide chains, each bound to an iron-containing haem group. This iron binds to oxygen.
Each red blood cell contains ? molecules of haemoglobin
~280 million
What is a prosthetic group?
A “helper” molecule, enabling other molecules too be biologically active. e.g. harm.
Haem is…
A flat molecule of four pyrrole groups, held together by =C- groups with an iron atom at the centre.
The collagen super helix is known as
Tropocollagen
Several collagen proteins form…
Collageen Fibril
Several collagen proteins form…
Collageen Fibril
Collagen fibrils form to create…
Collagen Fibres
What % of collagen is made from glycine
35%
What benefit does glycine give to the composition of collagen
glycine side chain is only H, so it is small and this can form more and stronger hydrogen bonds creating a stronger protein.
What conditions might cause a protein to denature
Change in pH
high temp
exposure to certain chemicals
Define denaturation
A change in the shape of a protein that alters or destroys that proteins ability to function normally. A result of the breakage in bonds.
What is the test for the presence of protein
Biuret teest
How does the Biuret test work?
Equal volumes of sodium hydroxide and pale blue copper sulphate are added to a solution.
If the solution turns purple there is protein present.
Photosyntthesis requires CO2, H20 and which 4 other inorganic ions
Nitrogen, phosphorus, magnesium and calcium
Why does a plant need nitrogen?
Nitrogen is required to make amino acids (NH2 - amino group).
How does a plant absorb nitrogen?
Through nitrate ions (NO3-)
Why do plants need phosphorus?
For the phospholipid bilayer
For ATP and ADP
How is phosphorus absorbed in plants?
Through phosphate ions (PO43-)
Why do plants need magnesium?
It is a component of the Chlorophyll
How do plants absorb magnesium?
Through magnesium ions (Mg2+)
Why do plants need calcium?
It is a component of calcium pectate, found in the middle of lamellae plant cells.
How do plant cells absorb calcium?
Through calcium ions (Ca2+)
Two types of cell
Prokaryote and eukaryote
Organism with one cell
unicellular organism
What is a Unicellular organism?
Organism with one cell
Multicellulaar organism
organisms with multiple cells, i.e. humans and animals
Prokaryotic vs Eukaryotic cell
Eukaryotic cell is more than a thousand times bigger than a prokaryote
Eukaryote has a nucleus surrounded by a nuclear envelope and several other membrane-bound organelles. A prokaryote does not have a nucleus nor any other membrane bound organelles.
Prokaryotes almost never form multicellular organisms
What are three parts of cell theory
- All living organisms are composed of one or more cells.
- The cell is the basic unit of structure and organization in organisms.
- Cells arise from pre-existing cells.
Three types of unicellular organism
Chlamydomonas, Amoeba and Escherichia coli.
Differentiation
The process of specializing a cell
Organization of cells
Cells > Tissue > Organs > Systems
Typically, how big are eukaryotic cells?
10-100um in diameter.
Features of the cell membrane
- phospholipid bilayer allows tight control of what goes in and out of the cell
- Cholesterol within the bilayer to help make it more flexible
- Proteins
- Channel proteins (and carrier proteins)
- hybrid glycoproteins and glycolipids as recognition
Plasma membrane is –nm thick?
7-9nm thick
How big is the nucleus, roughly?
10-20um
What is the purpose of the nucleolus?
rRNA synthesis
The Endoplasmic reticulum is…
A network of membranes folded into cisternae
What does the ER do?
transport material around the cell and chemically modifies them.
Two types of ER
rough and smooth
What is the rough ER?
The ER with lots go small ribosomes attached. These ribosomes are where the polypeptide chains of amino acids are assembled.
Where do you find ribosomes?
At the rough ER and scattered around the cytoplasm
What are the constituent parts of a ribosome?
ribosomal RNA (rRNA) and protein. Eukaryotic ribosome is 80S and is bigger than the 70S found in prokaryotic cells
What is the smooth ER?
Important for making , modifying and transporting lipids
Mitochondria
Where aerobic respiration takes place - ATP is produced here
Found richly in muscle cells because movement and biosynthesis require energy
How big are mitochondria?
~ 0.5-1.5 um wide and 3-10 um long.
Smaller than the nucleus
Structure of the mitochondria
Surrounded by two membranes
The inner membrane folds into the cristae where many enzymes associated with respiration are attached
The rest of the organelle is called the matrix
Small circular molecules of NDA are also located in the mitochondria matrix.
What is a Golgi?
A stack of membrane bound sacs or cisternae, each similar to a short section of smooth ER
What does the Golgi do?
modifies and transports materials like proteins.
New sacs containing material join from the rough ER on to one side of the Golgi, move through and eventually are pinched off as vesicles containing the modified material on the other side.
What are the potential downstream applications of the Golgi vesicles?
Some of these vesicles then fuse to the cell membrane and release the contents into the ECM. This is particularly important in secretory cells.
Other vesicles form lysosomes which fuse with vacuoles containing old, worn out organelles, or ingested food particles to digest them.
What is a lysosome?
Small spherical vesicles bound by a single membrane.
They contain a concentrated mixture of ~50 hydrolytic enzymes which are produced in the rER and modified in the Golgi.
What is a vacuole?
Membrane bound containers
Organelle
A structure within the cytoplasm of eukaryotic cells that performs a discrete function. With the exception of ribosomes, organelles are surrounded by at least one layer of membrane.
Structure of the nucleus
double Nuclear membrane with nuclear pores which allow transport of macromolecules such as mRNA.
Chromosomes and nucleolus are contained within the nucleus and
What does a lysosome do?
Involved in the breakdown of imported food vacuoles, old organelles and harmful bacteria that have invaded the body and been engulfed by one of the body’s defense cells.
How do lysosomes work?
Once engulfed into a larger vacuole, lysosomes fuse with the vacuole and release their hydrolytic enzymes into it. As a result, the food, organelle or bacterium is digested and the products of digestion escape into the cytosol.
What is a centriole?
The cell has two centrioles, each comprised of nine triplets of microtubules.
Microtubules are short, hollow, unbranched cylinders composed of the globular protein, tubulin.
What is the function of centrioles?
Moving organelles around the cytoplasm, important during cell division as they become the spindle.
Positioning of the centriole
Occur in pairs normally at right angles from one another, just outside the nuclear membrane.
Which structure only occur in plant cells
Cell wall, chloroplast, vacuole.
What is the cell wall of plants made from?
Cellulose bound together with hydrogen bonds which form long, straight fibres known as microfibrils. Microfibrils combine at angled layers to form cellulose fibres.
Features of the cell wall
Fully permeable so any material can pass in and out
Because the microfibrils are slayed out in different directions/angles the cell wall can resist stretching in any direction
Function of the cell wall
Stop the cell from bursting by taking on too much water by osmosis
What is the layer than forms between two cell walls?
Middle lamella
What is middle lamella?
A gel-like layer that forms between two cell walls
What is middle lamella made from?
Calcium pectate
Why are calcium ions important for plant growth?
Calcium pectate is the main component of the middle lamella. Middle lamella is the layer between two plant cell walls.
Plasmodesmata is…
Cytoplasmic connections between plant cells through gaps in their cell walls.
Part of the symplast pathway.
The name for the holes found in cell walls which link the cytoplasm of the two cells
Plasmodesmata
Lignin is…
A tough substance which is found in some cell walls
Vacuole is…
The cytoplasm and cell surface membrane of a plant cell are pressed firmly against its cell wall by a large, permanent fluid-filled vacuole.
Structure of the vacuole
Surrounded by a specialist single-membrane called the tonoplast - this is the barrier between the fluid contents of the vacuole and the cytoplasm.
Tonoplast
The single membrane surrounding thee large, fluid-filled vacuole found in plants.
How do animal and plant vacuoles differ?
Plant vacuoles take up most of the cell and are permanent
Animal vacuole are small and temporary
Prokaryotic cells
Typically only 0.2 2 um in diameter - much smaller than eukaryote
Lack most of the organelles found in eukaryotic cells, particularly the nucleus as they have a single circular DNA in the cytoplasm
Typically unicellular
Nucleoid
The circular DNA molecule found in prokaryotic cells.
Plasmids
In addition to the nuclei, some prokaryotic cells have small, circular DNA molecules in their cytoplasm. They don’t often contain many genes and some of the genes they carry are often anti-biotic resistance genes
70S ribosome
Involved in protein synthesis
Smaller than the 80S found in eukaryotes
Organelles not found in prokaryotes
mitochondria, chloroplasts, Golgi, ER
Cell wall of prokaryotes is made from:
peptidoglycan
What is Pili and flagella:
Pili help prokaryotic cells attach t surfaces or to each other.
Flagella help cells move around
Function of the prokaryotic cell wall
Gives it permanent shape
Protects against rupture due to osmosis
What is peptidoglycan?
Polymers of amino acids and sugars
Polymers of amino acids and sugars that form the prokaryotic cell wall…
peptidoglycan
What is the staining properties of gram negative and gram positive baacteeria
All bacteria have a cell wall, but some bacteria have additional layers Ono the outer surfaces of the wall.
Gram positive - thick walls made almost entirely of peptidoglycan. Will turn purple when stained with crystal violet.
Gram negative - thin walls of peptidoglycan with an additional outer membrane. High lipid content of this outer membrane prevents the crystal violet stain getting to the cell wall, so they will not turn purple with crystal violet.
What is the functional importance between gram negative and gram positive bacteria?
The outer, lipid-rich membrane of gram negative bacteria is relatively impermeable to antibiotics. Therefore, many gram-negative bacteria are antibiotic resistant, including penicillin.
What is horizontal gene transfer
When plasmids move between cells, transferring new genetic information.
What is a nucleotide
The monomer from which nucleic acids are formed. Each nucleotide comprises: - A pentose - A phosphate group - A purine or pyrimidine base
Specific structure of DNA
- Deoxyribose - a 5-carbon sugar (pentose). It has one Oxygen atom less than ribose. The oxygen is lost from the 2nd carbon.
- Phosphate - derrived from phosphoric acid
- Nitrogenous base -
What reactions join the three components of DNA?
condensation reactions - a water molecule is released in each case
Four nitrogenous DNA bases
Cysteine, guanine, thymine, adenine
Which of the five bases are purines and why.
Adenine and guanine
because they comprise of two rings
Which of the fives bases are pyrimidines and why.
Thymine, cysteine and uracil
Because the comrpise of only one ring.
What enzyme catalyses the binding of two DNA nucleotides and what type of reaction is it, what type of bond does it form and which groups is this bond between?
- DNA polymerase
- Condensation reaction
- A type of covalent bond called a phosphodiester bond 4. An OH of the phosphate group and the OH of the 3rd carbon of the deoxyribose. (OH + OH => O + H2O)
What is a phosphodiester bond
The covalent bond found between the phosphate group of one and the pentose ring of another nucleotide.
What type of bonds hold the two DNA strands together?
Hydrogen bonding between the nitrogenous bases
What cell cycle phase does DNA replication occur?
Interphase - S phase.
Four steps of DNA replication
- DNA helicase binds to the replication site, breaks the hydrogen bonds and 2. holds them separated as two separate templates.
- New, free nucleotides attach in a complementary sequence and hold together with hydrogen bonding.
- DNA polymerase catalyses the formation of the phosphodiester bonds between the new nucleotides.
- DNA ligase joins the larger polynucleotides together
Functions of DNA polymerase
Formtion of the phosphodiester bonds
“proof reading” of the DNA during replication
What is semi-conservative replication?
Each new double-stranded DNA molecule contains one of the two strands from the original molecule.
Which direction does replication work?
5’ -> 3’
