Biology AS Year 1

Glycogen

Glycogen

Polymer of alpha glucose with 1,4 and 1,6 glycosidic bonds, branched, insoluble, and compact.

Function of Glycogen

Branched with many ends for faster hydrolysis into glucose for respiration, and insoluble to prevent osmotic effect.

Structure of Starch (Amylose)

Polymer of alpha glucose, insoluble, coiled, and compact (hydrogen bonds) to store large amounts of glucose in a small space.

Function of Starch (Amylose)

Insoluble to prevent osmotic effect and can store large amounts of glucose in a small space.

Structure of Starch (Amylopectin)

Polymer of alpha glucose with 1,4 and 1,6 glycosidic bonds, branched with many ends for faster hydrolysis into glucose.

Structure of Cellulose

Polymer of beta glucose with 1,4 glycosidic bond, forming straight chains with hydrogen bonds between parallel chains, providing high tensile strength and rigidity to plant cell walls.

main polymer that forms the fungal cell wall

chitin

Benedict's Test for Reducing Sugar

Add Benedict's reagent to sample, heat in water bath at 60 degrees, positive result is a brick red precipitate.

Benedict's Test for Non-Reducing Sugar

Negative result for reducing sugar (stays blue), add HCL, heat in water bath at 100 degrees, add alkali to neutralize, then add Benedict's reagent, positive result is a brick red precipitate.

Test for Starch

Add iodine solution, positive result is a color change from orange to blue/black.

Emulsion Test for Lipids

Add ethanol, shake, then add water, positive result is a white milky emulsion.

Properties of Water

Metabolite, high specific heat capacity, high latent heat of vaporization, and habitat cohesion.

Test for Proteins

Add sodium hydroxide and heat at room temperature, then add copper sulfate solution, positive result for peptide bond is a color change from blue to purple.

describe the induced fit model

substrate and active site not 100% complementary. active site molds itself by changing tertiary structure (breaking h, ionic bonds and disulfide bridges) to become 100% complementary

enzyme substrate complexes form.

how an enzyme acts acts as a catalyst

lowers the activation energy

explain increasing substrate concentration on enzyme rate

as substrate conc increases more Enzyme substrate complexes form. but at higher substrate conc enzyme conc becomes limiting factor. (all filled up)

Eukaryotic

DNA in nucleus, membrane-bound organelles.

Prokaryotic

DNA not in nucleus, free in cytoplasm, no membrane-bound organelles.

Structure and Function of Cell Surface Membrane

Structure: phospholipid bilayer embedded with carrier, co-transport proteins. Function: isolates cytoplasm from extracellular environment, cell signaling, and recognition.

explain why phospholipids can form a bilayer but triglycerides cannot (3)

1. phospholipids have hydrophobic side and hydrophilic side

2. triglycerides are only hydrophobic

3. Hydrophilic/phosphate group attracts water

explain how unsaturated fatty acids cause membrane fluidity

Double bonds/unsaturated fatty acids cause bends/kinks in fatty acid tail

(Membrane more fluid because) phospholipids

further apart

suggest how the structure of rough endoplasmic reticulum is different from the structure of smooth endoplasmic reticulum and how this is related to their functions.

1. Less phospholipids in rough and Presence of ribosomes in rough;

2. Rough – production/transport of proteins;

3. Smooth production modification packaging transport of lipids

Role of Cholesterol, Glycoproteins, Glycolipids in Cell Surface Membrane

Cholesterol reduces fluidity and strengthens phospholipid bilayer, glycoproteins and glycolipids are involved in cell signaling, recognition, and binding cells together.

Describe functions of bile salts.

1. Emulsify lipids/fats;

2. Increases surface area (of lipid/fat) for (increased) lipase activity

3. Form micelles;

Structure of Nucleus

Nuclear envelope, nuclear pore, nucleolus.

Structure of Mitochondria

Double membrane, inner membrane folded to form cristae (increases surface area) matrix contains DNA, respiratory enzymes, lipids, and proteins.

Structure of Chloroplast

Double membrane, stack of thylakoids form grana containing chlorophyll for photosynthesis, stroma is a fluid-filled matrix.

Common Cell Adaptations

Folded membrane/microvilli increase surface area, many mitochondria for faster respiration and increased ATP, walls one cell thick for a short diffusion pathway.

why are viruses Referred to as Particles

Acellular - no cell membrane

non-living - no metabolism

cannot self-reproduce or respire

Structure of a Virus Particle

Linear genetic material and viral enzymes surrounded by capsid with attachment proteins.

Role of Attachment Proteins on Viral Particles

bind to specific receptor on t helper cells.

Outline What Happens During Interphase

G1 - protein synthesis and cell size doubles, S - DNA replication, G2 - organelles divide.

Purposes for Mitosis

Produces 2 genetically identical daughter cells for growth, cell replacement/tissue repair, and asexual reproduction.

Prophase

Chromosomes condense, spindle fibers form, nuclear envelope and nucleolus break down.

Metaphase

Sister chromatids line up at the equator of the cell by spindle fibers attached to centromere.

Anaphase

Spindle fibers contract, centromere split, sister chromatids split and chromosomes pulled to opposite poles of the cell.

Telophase

Chromosomes decondense, new nuclear envelope forms around each set of chromosomes, resulting in 2 nuclei.

Prepare Temporary Root Tip Mount

Cut thin layer of sample, stain with dye, use mounted needle at 45 degrees to place coverslip ensuring no bubbles enter.

Procedure for Root Tip Squash

Prepare temporary mount of tissue, place on optical microscope using lowest microscopic lens, calculate number of cells in a stage of mitosis, and calculate mitotic index.

describe how to isolate a sample of specific organelle

1. homogenise to break open cells and release cell contents using pestle and mortar

2. filter to remove any whole cells and cell debris

3. place in ice cold, isotonic buffered solution to reduce enzyme activity and prevent osmosis so cells don’t burst or shrink

4. place in a centrifuge and spin on low speed to collect nucleus first (most dense)

5. spin at higher speed to collect mitochondria and chloroplasts they settle out

Howe Cancer Treatments Control Rate of Cell Division

Prevent DNA replication, inhibit metaphase and anaphase.

Binary Fission

DNA replicates, plasmid replicates, cell elongates separating the 2 DNA, cell membrane contracts, cytoplasm divides, and cell splits into 2 cells.

Viral Replication

Attachment proteins bind to receptors on T helper cells, injects viral RNA into host cell, reverse transcriptase enzyme converts RNA into DNA, new viral proteins are produced, and new viral particles are assembled and released from host cell.

the stages of phagocytosis

1. Phagocytes attracted to pathogens by chemical products of the pathogen
2. receptors on phagocytes bind to chemicals on the surface of a pathogen
3. phagocyte engulfs pathogen into its phagosome
4. phagosome fuses with lysosome in the phagocyte
5. Lysosomes release hydrolytic lysozyme enzymes which break down pathogens and uses antigens of pathogen to present on antigen-presenting cell

t cell - cell mediated immune response

1. receptors on specific t helper cell bind to complemenntary antigen on antigen presenting cell

Increase in Antibiotic Resistant Bacteria

Mutation causes allele for resistance in bacteria, selection pressure (antibiotics) leads to an increase in frequency of resistant alleles/bacteria over time.

Use of Aseptic Techniques to Transfer Liquid Culture onto Agar Plate

1. Wash hands with soap,

2. use sterile plate and pipette,

3. flame the neck of bottle to kill any bacteria/microorganisms

4. lift lid of agar plate at an angle.

role of a helper T cell.

1. stimulates phagocytosis

2. stimulates b cells

Primary Structure of Protein

Sequence/order of amino acids that make up a polypeptide chain. joined together by peptide bonds.

Secondary Structure of Protein

Formed by hydrogen bonding to form either alpha helix or beta sheet.

Tertiary Structure of Protein

further folding of the secondary structure, held together by Hydrogen bonds, disulfide bridges, ionic bonds create active sites in enzymes.

Quaternary Structure of Protein

More than one polypeptide chain.

Define universal, non-overlapping and degenerate in terms of the genetic code

1. universal - The same codon/triplet always codes for the same amino acid

2. non overlapping - (Adjacent) codons/triplets do not overlap

3. degenerate - More than one codon/triplet codes for each amino acid

MRNA Production in the Nucleus (Transcription)

DNA helicase breaks hydrogen bonds, free RNA nucleotides line up alongside the template strand via complementary base pairing, forming new h bonds and RNA polymerase catalyses the formation of phosphodiester bonds in the sugar phosphate backbone rna helicase breaks new h bonds to form pre mrna and pre-mRNA is spliced to remove introns.

Polypeptide Formation by Translation of MRNA

MRNA attaches to ribosomes, tRNA anticodons bind to complementary MRNA codons, tRNA carries a specific amino acid and peptide bonds form between 2 amino acids using ATP, and TRNA is released as the ribosome moves along MRNA to form a polypeptide chain.

Enzymes Involved in Protein Digestion

Endopeptidases break peptide bonds in the middle of polypeptide, exopeptidases break peptide bonds at the end of polypeptide, and dipeptidases break dipeptide into amino acids.

Fluid Mosaic Model

Phospholipid bilayer containing hydrophilic head facing outwards, hydrophobic fatty acid tails facing outwards, and carrier proteins embedded within the bilayer to allow passage of polar larger molecules.

Role of Cholesterol and Glycolipids in Membranes

Cholesterol reduces fluidity to make membranes more stable, glycolipids are involved in cell recognition and cell signaling.

Factors That Affect Membrane Permeability

Temperature and pH.

Fick's Law

Surface area x concentration gradient/diffusion distance.

Sodium Ions in Co-Transport of Glucose

Na+ ions are actively transported out of cells into the lumen, creating a diffusion gradient for glucose to enter the cell via facilitated diffusion.

explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake

larger animals = smaller SA:VOL ratio.

specialised system provides a shorter diffusion pathway so faster rate of diffusion of oxygen.

Structure of the Heart Chambers

Atria have thin walls and are elastic to stretch when filled with blood, ventricles have thick muscular walls to pump blood under high pressure.

Structure of the Vessels

Arteries have thick walls to withstand high pressure, veins have thin walls due to low pressure and valves to prevent backflow.

Atrial Systole

Atria contract increasing pressure in atria and AVV valves open to allow blood to enter ventricles.

Ventricular Systole

Ventricles contract, increasing pressure causing AV valves to close (prevent backflow) and SL valves to open to allow blood to flow into arteries.

Structure of Capillaries

1. Walls one cell thick (shorter diffusion distance so faster rate of diffusion,

2. narrow (shorter diffusion distance

3. low pressure (more time for diffusion)

4. lots and highly branched for a larger SA:VOL ratio.

Tissue Fluid at the Arteriole End of the Capillary

Blood at arteriole end of capillary under high hydrostatic pressure forces tissue fluid out of capillaries, lowering water potential in the capillaries. proteins too large to leave through bilayer so remain in the capillary

Tissue Fluid at the Venule End of the Capillary

high water potential outside capillary and low water potential of blood so water diffuses back into the capillary via osmosis.

Structure of Hemoglobin

Globular, water-soluble, 4 polypeptide chains each carrying a heam group (quaternary structure).

Increased Partial Pressure of O2 and Affinity of Hemoglobin

Affinity of hemoglobin increases.

Bohr Shift (Effect of CO2)

CO2 reacts with water to form carbonic acid, lowering the PH of blood, altering the tertiary structure of Hb so it has a lower affinity for O2, allowing for higher rates of respiration.

Cooperative Binding

After the first oxygen molecule binds to haemoglobin, the protein changes shape and alters tertiary structure by breaking bonds (ionic disulfide hydrogen), making it easier for the next oxygen to bind, speeding up the binding of the remaining oxygen molecules.

Interpreting the pO2 Curve

At low PO2, oxygen binds slowly to hemoglobin, resulting in low saturation. At high PO2, oxygen binds quickly to hemoglobin, resulting in high saturation.

Equation for Cardiac Output

Cardiac output = heart rate x stroke volume.

Cohesion Tension Theory (Transpiration)

1. Water leaves through the stomata via evaporation, lowering water potential in spongy mesophyll cells
2. water is drawn up the xylem walls from the roots to the top of the xylem creating tension
3. cohesion - water forms H bonds between adjacent water molecules creating continuous columns of water
4. adhesion - tension between water molecules and xylem walls

Transport of Sugars in Plant Stems (Translocation)

1. H+ ions actively transported into companion cells,
2. sucrose transported into phloem through companion cells via cotransport with H+ ions, lowering water potential in the phloem
3. water moves into the phloem from the xylem via osmosis, creating high hydrostatic pressure in the phloem forcing sucrose down the phloem towards the sinks, where sugars are stored or used for respiration.

describe inspiration

1. Diaphragm contract and flattens/pulled down

2. External intercostal muscles contract and rib cage pulled up and out

3. volume increase and pressure decrease in thorax/lungs

describe inspiration

1. Diaphragm relaxes and becomes dome shaped.

2. External intercostal muscles relax and rib cage pulled down and in

3. volume decrease and pressure increase in thorax/lungs

Gas Exchange in Insects

Gases (O2 and CO2) move in and out of the tracheae through spiracles, allowing for diffusion, and contraction of muscles in tracheae enables mass movement of air in and out.

Gas Exchange in Fish

Fish opens its mouth to enable water to flow in, then closes its mouth to increase pressure, allowing water to pass over lamellae for O2 to diffuse into the bloodstream and waste CO2 to diffuse into the water, which flows back out of the gills.

Counter Current Exchange System

Blood and water flow in opposite directions, maintaining a high concentration of O2 in water, maintaining a steep concentration gradient along the whole length of lamellae allowing for a faster rate of diffusion of O2 into the bloodstream.

Adaptations of a Leaf for Efficient Gas Exchange

Thin/flat for a short diffusion pathway and large SA:VOL ratio, many pores (stomata) for easy gas entry, and air spaces in mesophyll for gas movement.

Pathway Taken by Air in Mammalian Gaseous Exchange System

Nasal cavity → trachea → bronchi → bronchioles → alveoli.

Function of the Nasal Cavity

Good blood supply warms air entering lungs, and goblet cells in the membrane secrete mucus which traps dust and bacteria.

Function of Trachea

Carries air to the bronchi, has a wide tube supported by C shaped cartilage, and lined by ciliated epithelium cells.

Function of Bronchi

Allows passage of air into bronchioles, supported by rings of cartilage, and lined by ciliated epithelium cells.

Function of Bronchioles

Allows for passage of air into alveoli, has muscle and elastic fibers for easy contraction and relaxation during ventilation.

structure and Function of Alveoli

Site of gas exchange, lined with epithelium cells, walls only one cell thick (shorter diffusion distance), and a network of capillaries for a large SA:VOL ratio.

Tidal Volume

Volume of air we breathe in and out during each breath at rest.

Breathing Rate

Number of breaths we take per minute.

Genetic Diversity

Variation in alleles within a population.