Cells, Biological Molecules, Membranes, Enzymes (2) Flashcards
Benedict’s quantitative test: If the reading for the unknown glucose solution does not fit on the range of the calibration curve, i.e. suggests a concentration greater than 1%, what could be done to obtain an accurate value for its concentration
dilute the unknown eg. serial dilution, and then calculate the original eg. multiply.
formula of disaccharide sugar
C12H24O12 - H2O (condensation reaction) = C12H22O11
summarise the condensation reaction to form a peptide bond
The hydroxyl group in the carboxylic acid of one amino acid reacts with a hydrogen in the amine group of another amino acid. A peptide bond is formed, water is produced. Example of anabolism. Resulting compound is a dipeptide.
what are the advantages and disadvantages of laser scanning confocal microscopes (4+1)
ADV:
- >living things can be viewed –> movement observed*
- >3D images can be produced by using several focal planes (different depths of field) **
- >non-invasive eg. used in detection of eye diseases **
- >fluorescent staining allows structures to be compared*
- *not in light microscopes*
DISADV:
>lower resolution than electron microscopes (shorter wavelength because not using light)
which adaptations does an erythrocyte have specific to its function
CONCAVE SHAPE; LARGE SURFACE AREA; hbfadglbf
THIN MEMBRANE;
describe the structure of cellulose
Alternate beta-glucose monomers are upside-down in order for B-1,4 glycosidic bonds to form. This creates a straight chain.
Around 80 chains form H-bonds together to form a microfibril. Microfibrils form H-bonds to make a macrofibril, which in turn produce fibres. INTERmolecular H-bonds to support structure.
what are multipotent stem cells
cells that can produce only cells of a closely related family of cells
eg. haemopoietic adult stem cells in the bone marrow differentiate into erythrocytes, platelets, macrophages, neutrophils etc.
what is the function of the R group
to form different bonds with other amino acids, leading to the long chains of amino acids to fold in a certain way. This will affect secondary, tertiary and quaternary structure and therefore produce a specific protein.
what is potency for cells
it specifies the differentiation potential of the stem cell i.e. how many different types of cell a stem cell can become
why are enzymes important to organisms
they allow reactions to occur at the temperatures within cells. Otherwise, metabolic reactions would occur too slowly, and the organism would die.
they also allow fine control over rate of reaction.
name the polysaccharide in fungi and insects (+ where)
CHITIN in the exoskeleton of insects in fungi cell walls
what was the initial hypothesis for how enzymes work
the lock and key hypothesis; the active site is EXACTLY complementary to the substrate and during the reaction the active site does not change shape, allowing it to continuously bind to substrates, forming enzyme-substrate complexes
what is glucose + fructose
sucrose- transport sugar in plants
what are the axes for a calibration curve
y axis = % transmission of red light x axis = concentration of glucose
how is glucose stored in plants and fungi
-stored as two forms of starch.
the starch is in grains in amyloplasts in the cytoplasm of plant cells
-stored as glycogen in fungi
why are enzymes specific to one type of reaction only
each enzyme has a specific tertiary structure (the overall 3D shape of the enzyme, involving coiling and pleating of the secondary structure) that gives it a specific active site complementary to a specific substrate. The tertiary structure is ultimately determined by the primary structure.
what is a polymer
a chain of repeating units, monomers, linked by covalent bonds
what is an ‘organic’ molecule
one that contains C and H
name the fibre appearance and whether it is voluntary/involuntary, uni/multinucleate for each of the three types of muscle cell
SKELETAL = striated, voluntary
multinucleate
CARDIAC = striated, intercalated (branches), involuntary
uninucleate
SMOOTH = unstriated, spindle-shaped, involuntary
uninucleate
summarise the basic structure of an amino acid monomer
A carbon atom (C) bonded to a hydrogen atom (H), an amine group (NH2) (base), a carboxyl group (COOH) (acid), and a variable R group, of which there are 20, giving the 20 main essential amino acids in humans.
what is a carboxyl group and where are they found, what is their compound name
a carbon bonded to a hydroxyl group and double-bonded to an oxygen atom (—COOH) found in amino acids and triglycerides carboxylic acid is the compound name
what is a microscope
an instrument employing lenses to produce a magnified image and fine details of objects too small to see with the naked eye
how to calibrate a light microscope
an eyepiece graticule inside the microscope has no units. it remains unchanged whichever objective lens is in place
we use a stage micrometer to work out how many (um) are in each division on the eyepiece graticule
what is the structure of haemoglobin
two alpha-polypeptide chains and two beta-polypeptide chains
+ an inorganic prosthetic haem group
the haem group contains an iron atom in a porphyrin ring (chlorophyll anyone?)
it has an overall tertiary structure of mainly alpha-helices
what are the functions of Ca(2+), potassium K(+) and sodium Na(+) ions
Ca(2+) calcium ions nerve impulse transmission, muscle contraction Na(+) sodium ions nerve impulse transmission, kidney function K(+) potassium ions nerve impulse transmission, stomatal opening
what is the main property and formula of monosaccharides
they are soluble and have the general formula (CH2O)n where n is = or >3.
what are the bonds involved with the different levels of protein structure
primary- peptide
- secondary*- intramolecular hydrogen bonds
- tertiary*- hydrogen (weakest), ionic (form between oppositely charged R-groups), disulfide/covalent (bonds or bridges, strongest of all, only form between S-containing R-groups), hydrophobic/hydrophilic interactions (weak, between polar and non-polar R-groups)
- quaternary*- “ as tertiary: hydrogen, ionic, disulfide/covalent, hydrophobic/hydrophilic interactions
Benedict’s quantitative test: If the reading for the unknown glucose solution does not fit on the range of the calibration curve, i.e. suggests a concentration greater than 1%, what could be done to obtain an accurate value for its concentration
dilute the unknown eg. serial dilution, and then calculate the original eg. multiply.
what are the functions of H+ and NH4+ ions
H+ hydrogen ions catalysis of reactions, pH determination, chemiosmosis
NH4+ ammonium ions production of nitrate ions by bacteria
what are totipotent cells
cells that can differentiate into ALL types of cell
name and give one sentence describing the four parts of a sperm cell (spermatozoon)
- acrosome at top of head, contains hydrolytic enzymes to digest outer layers of ovum follicle to reach cytoplasm/nucleus.
- head contains haploid nucleus (n) for fertilisation of an ovum for subsequent production of diploid zygote (2n).
- midpiece contain large quantity of mitochondria to produce ATP by AR to provide energy for tail motion
- tail: flagellum/undulipodia contains contractile microtubule fibres to enable movement/swimming
measuring cells is done in…
micrometers (um)
what gives collagen added strength (i.e. not from its structure)
collagen molecules form staggered COVALENT CROSS LINKS with each other, forming more chains. Collagen molecules wrapped around each other from COLLAGEN FIBRILS (and then collagen fibres)
what are the functions of OH- and Cl- ions
- OH- hydroxide ions* catalysis of reactions, pH determination
- Cl- chloride ions* balance the positive charge of sodium and potassium ions in cells
what is the structure of an amino acid
a carboxyl group (–COOH attached to carbon skeleton) and an amine group (NH2 attached to carbon skeleton, a H attached to the C and a variable R-group attached to the C. The different R-groups result in different amino acids (of which there are 20).
what is fluorescence
the absorption and re-radiation of light
what are the 3 functions of intermediate filaments
-anchor the nucleus -allow cell to cell signalling eg. antigens, WBCs, ECM -allow cell to cell adhesion in tissues
what is the first monosaccharide
C3 H6 O5 = triose. eg. TP/GP in Calvin cycle/glycolysis
why is staining used with light microscopes
the interior of cells is often transparent
staining allows different components of cells to be distinguished between
provides contrast between structures
how can you describe the two parts of a phospholipid
The hydrophilic polar ‘head’ and the hydrophobic nonpolar ‘tail’
what are pluripotent stem cells
the descendants of totipotent cells
they can differentiate into cells derived from the three germ layers of endoderm, mesoderm, ectoderm
eg. ectoderm can differentiate into skin, nerves, hair
what is the limit of an optical microscope’s resolution
the resolution can be no greater than 0.2µm, because that is half the wavelength (400nm/0.4µm) of visible light.
Light waves can resolve objects greater than or equal to 400nm apart.
how is tertiary structure broken
increasing TEMPERATURE to increase kinetic energy, causing the bonds to vibrate and not maintain the shape of the protein and eventually break (they are not covalent so not very strong). Once it has lost its shape, a protein is DENATURED.
which cells can differentiate into all cell types
TOTIPOTENT stem cells
what is collagen
an insoluble fibrous protein
List the property, structure, type of bond, found in, and function of AMYLOPECTIN
P = insoluble, granular S = polysaccharide, branched TOB = a-1,4 glycosidic bonds and a-1,6 glycosidic bonds, intramolecular H-bonds FI = chloroplasts (as starch granules) tubers, storage organs F = energy store in plants
how is a dipeptide formed
a covalent bond is formed between two amino acids, removing the OH from the amine group and the H from the carboxyl group during the condensation reaction. the reaction is catalysed by peptidyl transferase
name the 5 cations we need to know
Ca2+ calcium ions
K+ potassium ions
Na+ sodium ions
H+ hydrogen ions
NH4+ ammonium ions
list 6 differentiated/specialised cells/tissues in animals
CELLS:
erythrocytes (RBCs
neutrophils (WBCs
sperm cells
muscle cells
TISSUES:
cartilage
epithelial tissues; single or multiple sheets of cells covering internal and external surfaces of organs and lining tubes eg. squamous epithelia, ciliated epithelia
outline the lipids qualitative emulsion test
- Lipids are soluble in alcohol but not water. The emulsion test dissolves any present lipids in ethanol, then adds water, causing the lipid to form a precipitate/emulsion. 2. Ethanol followed by distilled water are added to the samples. A piece of black paper is placed behind the sample to view the precipitate more clearly. 3. Mash the sample, allow solid to settle at the bottom of the tube, pipette the ethanol into a new test tube, add distilled water, use black paper.
what is the cytoskeleton made of and what is its function
it gives strength, shape, support and movement within the cell. It is made of intercellular proteins: microfilaments, intermediate filaments and microtubules.
what is glucose + galactose
lactose- sugar found naturally in milk
what is the function of collagen
bone, cartilage, connective tissue formation prevents blood from bursting artery walls at high pressures
what are the functions of NO3-, HCO3- and PO43- ions
NO3- nitrate ions nitrogen supply to plants for AA and protein synthesis
HCO3- hydrogen carbonate ions maintenance of blood pH
PO43- phosphate ions cell membrane formation, nucleic acid and ATP formation, bone formation
name the 5 anions that we need to know
Cl- chloride ions
HCO3- hydrogen carbonate ions
OH- hydroxide ions
PO43- phosphate ions
NO3- nitrate ions
what is a cell
the unit of all living organisms
how has the hypothesis for how enzymes function ameliorated
the induced fit hypothesis states that the active site is NOT exactly complementary in shape to the substrate. The substrate induces a change in the shape of the active site so that it can be complementary and the enzyme reverts back to the original shape after the reaction.
name and explain the other 4 roles of water and the biological significance of those roles (DOILTDOW) (HCF) (SST) (AF)
- DENSITY OF ICE LOWER THAN DENSITY OF WATER; below 4’C, the molecules of H2O are further apart and therefore contains fewer molecules than an equal volume of liquid water, in a crystalline structure where each molecules is H-bonded to 6 neighbouring molecules. Therefore the ice floats, creating a barrier for the aquatic environment(insulation). -habitat: aquatic animals resist extreme cold and artic animals have a habitat on the surface -transport medium: density changes circulates nutrients 5. HIGH COHESIVE FORCES transport medium: as water is pulled up through the roots and xylem vessels due to evaporation from the leaves of the plant, the cohesive forces from H-bonds hold the column of water together within the cells. 6. STRONG SURFACE TENSION -habitat: collective strength of H-bonds between water molecules allow organisms to live on the surface eg. the water strider. 7. ADHESIVE FORCES -transport medium: as water is pulled up through the roots and xylem vessels due to evaporation from the leaves of the plant, adhesive forces of water to the cell walls help resist the downward force of gravity.
where are multipotent stem cells found
in adult stem cells eg. in the bone marrow
they are present in the adult body and developing embryo
in the cambium of the plant, to form xylem and phloem
outline the 4 stages of STOMATAL PORES OPENING
- K+ is pumped into guard cells.
- H2O follows in by osmosis
- guard cells become turgid
- cells move outwards and the pore is opened
(reverse occurs when pores closing)
Benedict’s quantitative test: Explain why the transmission of red light increases as the glucose concentration in the sample increases.
more glucose = more Cu2+O precipitate
and therefore less copper sulfate(CuSO4), leading to a lower intensity of blue colouration in the solution, and tf more red light transmitted through the solution.
what is glucose + glucose
what is the function of the disaccharide
maltose
produced from hydrolysis of amylose
found in germinating seeds
describe the first type of electron microscope
transmission electron microscope TEM
tissue/cell is infiltrated with resin, cut into very thin slices- diamond knife
beam of electrons is passed through slice of material
where electrons are absorbed = dark
where electrons come through = white
image has 2D flat appearance
objects can be magnified more than 500,000x
TEM has the highest degree of resolution (no figure needed)
name where the three types of muscle are located
SKELETAL = muscles, attached to skeleton
CARDIAC = in walls of the heart
SMOOTH = in the walls of internal organs
What is the difference in the location of KREBS CYCLE + OX PHOS in eukaryotes and prokaryotes
In the mitochondria of eukaryotic cells and the cytoplasm of prokaryotic cells.
what is cholesterol and what is its function
A hydrophobic sterol that sits between fatty acid chains within membranes to regulate the fluidity of the phospholipid bilayer to be neither too rigid nor too fluid.
(not too fluid at high temperatures by reducing phospholipid movement, not too rigid at low temperatures by hindering solidification as the phospholipids have less energy and more less)
how do laser scanning confocal microscopes work
a <em>single spot of focused light</em> is moved across a specimen which has been dyed using a fluorescent dye.
Light of a longer wavelenth is emitted and used to produce a magnified image.
describe the effect of substrate concentration on enzyme rate of reaction
- as substrate concentration increases, there are more successful collisions -tf there are more occupied active sites, and more enzyme-substrate complexes made -rate of reaction increases up to the optimum concentration of substrate, where substrate concentration is no longer the limiting factor
- all active sites are occupied and all enzymes present are working at the maximum rate = VMAX!! -tf increasing substrate concentration will no longer increase the rate of reaction, and the graph will plateau
give examples of the following roles of water:
- dissolving
- high latent heat of evaporation
- high cohesive forces
DISSOLVING:
PLANTS; Soil with nitrates, cytosol with nutrients in aquatic environments, xylem transports nutrients, phloem carries dissolved sucrose. ANIMALS; water in blood plasma allows transport of hormones, nutrients: glucose, AAs, minerals, vitamins, waste substances: urea, carbon dioxide
HIGH LATENT HEAT OF EVAPORATION: sweating, panting, evaporation from the mucus membranes, transpiration
HIGH COHESIVE FORCES: xylem
what are unipotent cells
cells that can produce only one cell type, but have the property of self-renewal (which distinguishes them from non-stem cells) eg. mother cells of gametes
what is the function of haemoglobin + how does it do this
Transport and carry oxygen in the blood.
The haem group contains an Fe2+ ion, onto which the oxygen molecules can bind.
what are the main 7 properties of cellulose
- HIGH TENSILE STRENGTH -strength of covalent glycosidic bonds between the B-glucose monomers, and between the parallel molecules of cellulose there is intramolecular H-bonding, which is collectively strong.
- EXTRA SUPPORT FROM STRUCTURE- cellulose molecules bond in parallel lines by intramolecular H-bonds to form microfibrils. Microfibrils running in different directions make a H-bonded bundle = a macrofibril.
- SUPPORT- there is no cytoskeleton
- ALLOWS DIFFUSION OF WATER INTO CELLS as the cell wall is fully permeable to water and ions
- PREVENT BURSTING when turgid, turgidity gives the cell strength and support
- MACROFIBRILS MIXED dependent on function
- with lipids/cutin for waxy cuticle, suberin in roots and lignin in xylem walls - ANIMALS DO NOT HAVE CELLULASE ENZYME to digest cellulose
why are starch and glycogen good stores of energy (3 reasons) (long)
- INSOLUBLE IN WATER- significant for animal cells that do not have a cell wall. Therefore water entering the cell would: 1. affect the water potential of the cell and 2. cause osmotic swell and eventual cytolysis. 2. MONOMERS EASILY HYDROLYSED- tf there can be a rapid release of energy, especially if branched like amylopectin and glycogen- the a-glucose monomers are hydrolysed by enzymes. 3. COMPACT- therefore they do not require a large area for storage, especially when branched like amylopectin and glycogen. They are granular i.e. they form dense granules in the cell; Starch forms in chloroplasts and glycogen mainly in the liver and muscle cells.
describe the second type of electron microscope
specimen is shadowed with a layer of metal and carbon
it is scanned by a fine electron beam, which is reflected from surface of specimen and transmitted to a detector
3D APPEARANCE
objects can be MAGNIFIED 50,000x
what is a phosphate group and where is it found, what is its compound name
A phosphorus atom bonded to four oxygen atoms. One is double bonded, one bonds to carbon skeleton, two have negative charges.
Found in phospholipids, DNA, RNA, ATP, NADP
Name of compound is organic phosphates
what are stem cells (3 things)
undifferentiated primal cells common to all multicellular organisms
they retain the ability to renew themselves via cell division
they can differentiate into a wide range of different cell types, depending on their potency
what is an artefact
an artificial component that obscures the clear view of an anatomical structure, often arising from the preparation of the specimen/slide.
What are the similarities and differences between the two forms of starch (plant polysaccharide)
Known collectively as starch, a chemical energy store in plants produced from photosynthesis . Made of alpha-glucose monomers. Amylose is linear. Amylose contains only a-1,4 glycosidic bonds. The angle of the bond causes it to form a helical structure, strengthened by intramolecular H-bonds within the molecule. Therefore it is more compact and a lot less soluble than the glucose molecules used to synthesise it. Amylopectin is branched. Amylopectin contains a-1,4 glycosidic bonds and 1,6 glycosidic bonds between carbon 1 and carbon 6. Both have intramolecular H-bonds to hold helical structure.
what are the different types of cellulose (3 marks)
Cellulose can be mixed with:
- lipids/cutin for waxy cuticle*
- suberin in roots*
- lignin spiralled in xylem walls*
how is a triglyceride formed
The glycerol loses three OH
each fatty acid loses HO
in its place there is an O atom
