Unit B 死记烂背 Flashcards
B1.2
Properties and Functions of 7 Proteins
Cellulose - flexible - plant cell wall
Actin - polymerizable - muscle, microfilaments
Albumin - hydrophilic - hormone/vitamin transport
Collagen - ery high tensile strength - skin, ligaments, cartilage, sclera
Immunoglobulin - 20% blood plasma - immunity
Rhodopsin - low-light vision (rod receptors)
Keratin - high tensile strength - hair, skin, nails
B1.2
Levels of Polypeptide Structure
Primary Structure - amino acid sequences
Secondary Structure - folding of peptide chains into helices or sheets
Tertiary Structure - folding of polypeptide via ionic, disulphide and hydrogen bonds
Quaternary Structure - interaction of polypeptides and prosthetic groups
B1.2
4 Properties of Globular Proteins
- tertiary structure
- for metabolism
- water-soluble
- high pH/temperature sensitivity
B1.2
4 Properties of Fibrous Proteins
- secondary structure
- for structure
- water-insoluble
- low pH/temperature sensitivity
B2.1
7 Point Explanation of Cholesterol Effect on Membrane Fluidity
- polar group faces aqueous external environment
- non-polar regions faces cell interior
- rigid steroid strucutre strongly interacts with phospholipids
- increases fluidity at low temperature by interfering with packing
- decrease fluidity at high temperature by interfering with phospholipid mobility
- boradens or narrows phase transition of freezing
- prevents abrupt membrane fluidity changes
B2.1
6 Point Explanation of Effect of Temperature on Fatty Acid Saturation
- unsaturated tails are kinked so are less dense and have lower melting point
- excess unsaturated fatty acids increase membrane fluidity
- membrane fluidity needed for protein function
- unsaturated fatty acids prevent solidification
- at high temperature, more saturation to strengthen membrane
- to maintain appropriate membrane fluidity
B2.1
4 Point Explanation of Role of Phospholipids in Plasma Membrane
- hydrophilic phosphate faces aqueous external environment
- hydrophobic fatty acids face each other forming core
- low permeability to large or charged species
- effective patrtial permeability
B2.1
5 Functions of Proteins in Membranes
- ion channels for facilitated diffusion
- pumps for active transport
- glycoproteins for cell recognition
- cell adhesion
- hormone communication and reception
B2.1
5 Point Explanation of Function of Endocytosis and Exocytosis
- endocytosis - formation of vesicles by inward pinching of membrane
- exocytosis - fusion of vesicles with membrane
- strength and fluidity of fluid mosaic membrane
- energy needed in form of ATP to transport vesicles
- eg. phagocytosis and synaptic transmission
B2.2
5 Point Explanation for Diversity of Carbon Compounds
- carbon can form 4 covalent bonds
- covalent bonds provide stability to biological molecules
- can form chains and cyclic structures
- carbohydrates, fatty acids, amino acids
- sugars, lipids, proteins
B2.2
5 Point Explanation of Significance of Compartmentalisation
- organelle has specific function
- compartmentalisation separates incompatible reactions
- compartmentalisation allows correct concentration of metabolites
- eg. hydrolytic enzymes in lysosome are acidic
- eg. separate from neutral cytoplasm
B2.2
2 Functions of Nuclear Membrane
- protect DNA from other cytoplasmic reactions
- prevent polymorphisms that would be disadvantageous for the organism
- separates transcription and translation
- post-transcriptional modification creates protein variants
B2.2
2 Point Explanation of Function of Nuclear Pore
- protein-lined channel in nuclear envelope
- regulate transport of folded proteins and ribosomal components
B2.2
6 Adaptations of Organelles
- nuclear pore allows mRNA to travel for translation
- free ribosomes synthesise proteins for intracellular use
- rER ribosomes synthesise proteins for extracellular use
- folded mitochondiral membrane increases surface area for respiration
- folded chloroplast membrane increases surface area for light-dependent reaction
- range of pigments absorbs light for photosynthesis
B2.2
3 Point Explanation for Polysome Function
- ribosomes translating same RNA
- polysomes simultaneously produce multiples copies of same protein
- cell needs multiple copies of particular protein
B2.2
4 Step Action of Clathrin in Endocytosis
- receptor-mediated endocytosis
- clathrin binds to surface receptor
- polymerisation into clathrin-coated pit
- invaginated membrane breaks off to form vesicle
B2.3
4 Point Explanation for Effect of Size on Heat Loss
- large organisms have low SA:V ratio
- limited heat loss by radiation
- small organisms have high SA:V ration
- significant heat loss by radiation
B2.3
6 Properties of Stem Cells
- undifferentiated
- potent
- capable of self-renewal
- found in all multicellular organisms
- only few adult cells retain stem cell properties
- unipotent, multipotent, pluripotent, totipotent
B2.3
6 Point Explanation of Role of Stem Cell Niches
- niche of self-renewing undifferentiated stem cells
- dormant cells
- acitvate or repress genes
- vascular niche in bone marrow for stem cell mobilisation
- follicles between hair erector muscle and subaceous gland
- growth and resting phases
B2.3
3 Point Explanation of Morphogen Function
- variation in cell-signalling morphogen concentration
- response of gene expression determines direction and extent of growth
- length of digits, nose location
B2.3
3 Point Explanation of Pneumocyte Function
- Type I - gas exchange between alveoli and capillaries
- Type II - lipoprotein and phospholipid surfactant
- surfactant reduces surface tension to sustain smooth movement of alveolar walls
B2.3
2 Adaptations of Type I Pneumocytes
- flat - reduced diffusion distance
- interconnected - prevent tissue fluid leaking into alveolar air space
B2.3
5 Adaptations of Cardiac Muscle
- cylindrical branching of fibres - fast propagation of contraction signal
- capillaries and mitochondria - respiration for energy
- intercalated discs - transfer of electrical impulses
- gap junctions - synchronised electrochemical gradient
- branching - connection and synchronisation of adjacent cells
B2.3
3 Adaptaions of Ova
- large cytoplasm - nutrition for zygote development
- cortical granules - prevent polyspermy
- moved by cilia in fallopian tube - conserve energy
B2.3
3 Adaptations of Sperm
- middle piece with mitochondria - energy to travel
- acrosome - difestive enzymes facilitate ovum entry
- streamlined + flagellum - swim through fluid
B3.1
5 Properties of Gas Exchange Surfaces
- high surface area
- permeability
- thin tissue layer
- moist surfaces dissolve gas
- maintains steep concentration gradient.
B3.1
3 Adaptations of Alveoli
Alveolar fluid - moistens alveolar walls for gas diffusion
Surfactant - prevent collapse of alveolar walls during exhalation
Many small alveoli next to capillaries - short diffusion distance
B3.1
6 Step Process of Inspiration
- Diaphragm contracts
- External intercostal muscles contract, internal muscles relax
- Ribcage moves up and out
- Increased thoracic volume
- Decreased thoracic pressure
- Air moves into the lungs
B3.1
6 Step Process of Expiration
- Diaphragm relaxes
- External intercostal muscles relax, internal muscles contract
- Ribcage moves down and in
- Decreased thoracic volume
- Increased thoracic pressure
- Air moves out of the lungs
B3.1
3 Plant Adaptations for Gas Exchange
- Thin and flat leaves - large surface area for gas diffusion and for light
- Hydrophobic waxy cuticle - reduces water loss
- Air pockets in spongy mesophyll- maintain concentration gradient for CO2 and O2
B3.1
5 Regions of Spirometry Graph
- Inspiratory Reserve Volume = maximum additional volume of air that can be inhaled
- Tidal Volume = fluctuation in volume of normal breathing
- Expiratory Reserve Volume = maximum additional volume of air that can be exhaled
- Forced Vital Capacity = total air that can be exhaled
- Residual Volume = volume of air in lung which cannot be exhaled
B3.1
3 Point Explanation for Foetal Oxygen Supply
- HbF has gamma peptides, HbA has beta peptides
- HbF has higher oxygen affinity than HbA (comparative Bohr shift)
- Foetus obtains oxygen through placenta
B3.1
4 Point Explanation for Haemoglobin Oxygen Carrying Capacity
- At low partial pressure, there are few successful collision of O2 with haem binding sties
- When one oxygen binds, conformational changes assist binding of second and third oxygen
- At high partial pressure, haemoglobin is highly saturated, there are few successful collisions
- Haemoglobin loads oxygen from cells with high partial pressures and unloads into cells with low partial pressure
B3.2
5 Step Process of Interstital Fluid Formation
- On the arteriole end, hydrostatic pressure is greater than osmotic pressure.
- Water and glucose move out by ultrafiltration into the space between cells, forming interstitial fluid and moves into cells.
- Metabolic waste products, CO2 and urea, move out of cells through the interstitial fluid.
- On the venous end, osmotic pressure is greater than hydrostatic pressure due to the high solute concentration in the plasma.
- Tissue fluid is returned to the circulation of lymphatic system.
B3.2
4 Step Process of Heart Systole
- SA nodes initiate contraction.
- Atrial systole.
- Electrical impulses travel through Bundle of His and to Purkinje fibres.
- Ventricular systole.
B3.2
3 Point Explanation of Evapotranspiration
- Evaporation of water vapour from stomata in leaves generates a negative pressure, drawing water upwards.
- Due to the hydrogen bonding between polar H2O molecules, water moves up in a continuous column.
- Adhesion of water to the xylem lignin walls also maintains the continuous stream. Adhesion additionally narrows the xylem diameter to assist with maintaining water transport.
B3.2
4 Step Process of Root Pressure Generation
- Abiotic factors do not favour evapotranspiration
- Active transport of mineral ions into root hair cells
- Increases solute concentration reduces water potential, causing water to move in by osmosis.
- Movement of water into the xylem generates positive hydrostatic pressure potential.
B3.2
3 Adaptation of Xylems
- Lignin - strength and waterproofness
- Pit cells - movement of water between adjacent cells in xylem
- Lumen has no cytoplasm - maximise water transport capacity
B3.2
8 Step Process of Translocation
- Bidirectional movement from source to sink
- Sucrose is produced in leaves by photosynthesis
- Sucrose is actively transported by the apoplast route
- Surcrose is loaded into companion cells
- High concentrations of solutes at the source cause uptake of water by osmosis
6 Water provides hydrostatic pressure for mass flow - Sucrose is unloaded / stored / used at sink
- lowers pressure at sink / creates pressure differential / water re-entry to xylem
B3.2
4 Adaptations of Phloem
- Perforation in sieve plates - sap flows freely
- Anucleate sieve tube elements - maximise phloem sap capacity
- Mitochondria in companion cells - active transport out of sources and into sinks
- Plasmodesmata - allows transport between siee tube elments and companion cells
B3.3
5 Regions of Sarcomeres
M line - organises myosin
Z disc - organises actin
H zone - myosin only
I band - actin only
A band - myosin and actin present
B3.3
10 Step Process of Sliding Filament Model
- Action potential travels across rough sacroplasmic reticulum
- Voltage gated Ca channels open, Ca efflux
- Ca binding to troponin causes conformational change
- Leaving of troponin removes tropomyosin
- ATP hydrolysis causes myosin head to change angle, storing chemical energy as potential energy
- Myosin forms cross-bridge with actin
- ATP and Pi release causes power stroke towards M-line
- Sarcomere contracts (8-10 nm)
- ATP attaches to myosin, cross-bridge breaks
- Repeated ATP hydrolysis supplies energy for repeated sarcomere contraction
B3,3
4 Functions of Titin
- helps the sarcomere return to its original length
- adds to force of contraction
- prevents overstretching, provides passive resistance to maintain structural integrity and health of muscle
- holds each myosin filament in the correct position between 6 actin filaments
B3.3
5 Components of Synovial Joints
- Synovial Fluid - reduces friction, nourishes articular hyaline cartilage
- Joint Capsule - seals synovial fluid, prevents disolocation
- Articular Cartilage - reduce friction, absorb shock
- Ligaments - prevents dislocation
- Tendons - medium between muscle and bone
B3.3
4 Reasons for Locomotion
- Foraging
- Escaping danger
- Mate selection
- Migration
B3.3
10 Adaptation of Dolphins
- Streamlined body shape, flippers, flukes, dorsal fin, smooth skin, even distribution of blubber - reduce drag
- Blubber around organs, low SA:V ratio - reduce heat loss
- Flippers - steering
- Fluke - propel dolphin
- Dorsal fin - prevents rolling over
- Low density blubber - buoyancy
- Blowhole - periodic breathing
- Separated mouth and lungs - prevent water entering lungs
- Large lungs, high alveoli capillary exposure, high myoglobin, high blood volume, high erythrocyte count, high haemoglobin concentration - oxygen storage and gas exchange
- Blowhole - whistles and clicks as communication
B4.1
6 Adaptations of Marram Grass
- Rolled leaves with hairs
- Stomata are located on the inside of the leaf
- Stomata are surrounded by hairs
- The inner epidermis is highly folded
- Deep root system
- Rhizomes
B4.1
3 Adaptations of Mangrove Plants
- Pneumatophores (aerial roots)
- Stilt roots
- Propagation
B4.1
Adaptations of 5 Plants to Abiotic Conditions
- Ferns grow large, thin leaves with high chlorophyll content.
- Cacti have a thick waxy epidermis to reflect sunlight and reduce transpiration.
- Tomatoes have heat shock proteins to protect against high temperatures.
- Rice plants can close the stomata during droughts to reduce water loss.
- Legumes have symbiotic relationships nitrogen-fixing bacteria.
B4.1
Adaptations of 5 Animals to Abiotic Conditions
- Polar bears and penguins have thick fur for insulation.
- Camels and kangaroo rats store water in the body.
- Nocturnal animals (eg. bats, owls) avoid diurnal predators.
- Herbivores have specialized teeth to digest plant tissue.
- Bats and ground squirrels hibernate to conserve energy.
B4.1
3 Limiting Factors of Coral Reef Growth
Temperature 23 - 29 C
pH 8.0 - 8.4
Water clarity
B4.1
3 Adaptations of Camels
- Thick skin and osmotic cells
- Fluctuating internal body temperature
- Fat-storing humps
B4.1
5 Adaptations of Cacti
- Thick waxy cuticle and epidermis
- Spikes
- Deep stoma, only opens at night
- Large stems
- Shallow roots
B4.1
4 Adaptations of Scorpions
- Slow metabolism
- Water-absorbing exoskeleton
- Venom and hard exoskeleton
- Excretion system produces semi-solid guanine
B4.1
3 Adaptations of Kangaroo Rats
- Seed diet
- Large hind legs
- Nasal passage specializes in water reabsorption
B4.1
3 Adaptations of Pitcher Plants
- Bright colours and scents
- Waxy internal rim
- Large superior lip
B4.1
2 Adaptations of Flying Lizards
- Streamlined limbs
- Patagium (elongation of thoracic limbs)
B4.1
3 Adaptations of Gibbons
- Hook-shaped hands, long arms
- Long legs
- Wide shoulder joints
B4.1
Adaptation of Orchid Mantis
- Camouflage against orchids
B4.2
6 Adaptations of Plants
- Phytochemicals
- Thick, rigid leaves with thorns and trichomes.
- Aerial roots
- Epiphyte behaviour (eg. orchids, strangler figs)
- Large leaf surface area (shrub layer)
- Camouflage
B4.2
2 Adaptations of Herbivores
- Strong mandibles, large teeth with thick enamel layer and tooth growth. Diastema.
- Insect stylets (proboscis in aphids)
B4.2
4 Adaptations of Prey
- Large field of view, small area of binocular vision, large ears
- Camouflage
- Defence mechanisms
- Collaborative grouping behaviour
B4.2
4 Adaptations of Predators
- Sharp teeth (esp. canines) and claws.
- Aggressive mimicry
- Sensitive hearing and olfactory organs, night vision
- Toxins or venoms.
B4.2
4 Properties of Herbivore Teeth
Incisor - Long, flat
Diastema
Pre-molar - Large, flat
Molar - Large, flat
B4.2
4 Properties of Omnivore Teeth
Incisor - Sharp
Canine - Pointed
Pre-molar - Large, flat
Molar - Large, flat
B4.2
4 Properties of Carnivore Teeth
Incisor - Sharp
Canine - Long, sharp
Pre-molar - Sharp
Molar - Large, flat
