Year One Flashcards
What organelles do plants and animal cells have
Animal
Nucleus vesicles lysosomes mitochondria rough and smooth er Golgi Cytoplasm membrane ribosomes
Plant
Nucleus cell wall membrane chloroplasts vacuole plasmids cytoplasm vesicles Golgi ribosomes
What organelles do eukaryotic cells have?
Lysosome 80s ribosomes chloroplasts membrane bound organelles, nucleus nuclear envelope mitochondria nucleolus grana rough and smooth er centriole
What organelles do prokaryotic cells have
70s ribosomes circular DNA Muriel cell wall cell membrane cytoplasm starch granules glycogen lipid droplets capsule plasmids flagellum pili
What are characteristics of viruses
Non living Can’t replicate on their own Have lipid envelope Capsid attachment proteins Receptors Nuclei acid
How do viruses replicate
Identify host cell via their receptors and attach
Endocytosis:lipid envelope fuses with membrane
Capsid disintegrates releasing contents into host cell
Virus uses host cells machinery to replicate
New virus cell forms and buds off
What is a carcinogen
What is a mutagen
Carcinogen: causes growth of cancer
Mutagen: causes damage to cells
What happens in phase two of mitosis
PMAT
1-prophase=chromosomes condense, nuclear envelope breaks down, nucleolus breaks down, centrioles and mitotic spindle fibres form
2-metaphase=chromosomes line up on metaphase plate, chromatids will attach to spindle fibres via centromere to spindle fibres
3-anaphase=chromatids pulled apart to opposite poles of cell by mitotic spindle fibres
4-telophase= spindle fibres disintegrate, nuclear envelope and nucleus reforms, the chromosomes become diffuse and a cleavage furrow forms
What are characteristics of plasmids
When daughter cell replicates one may get more than other
Can get from environment
Replicate on own
Can be altered to get certain characteristics
Don’t associate with proteins
How does cancer occur
A gene controlling cell cycle mutates, causing rapid and uncontrolled growth of cells
A lump of abnormal unspecialised cells that overwhelm an organ forms a tumour
What does benign and malignant mean
Benign- not cancerous, slow grower
Malignant- cancerous and fast grower, undergoes metastasis (lump breaks off and travels as lump around body and can infect any organ)
What is a proto-oncogene?
A gene that promotes cell division
If mutates into oncogene, they act excessively and cells will divide rapidly and uncontrollably
What is a tumour suppressor gene
It inhibits cell growth so if it mutates then inhibition no longer happens and the cells uncontrollably grow and divide
What’s definition of mitosis
A parent nuclei undergoes nuclear division to produce to genetically identical daughter cells which are identical to eachother and the parent cell
What happens in phase one of mitosis
Interphase
G1-cell doubles in size, protein synthesis and contents replicate
S-DNA replication (semi conservative)
G2-cell checks for any errors in replication, grows more, prep for mitosis
What happens in phase 3 of mitosis
Cytokinesis
Parent cell splits and separates
What is a plasma membrane
The boundary between cell contents and environment Made of phospholipids and proteins Semi permeable cell surface membrane Fluid Reform if broken
What are the functions of cell surface membrane
Help maintain homeostasis
Control movement of substances in and out
Forms boundary between cell and environment allows for different conditions for different reactions inside and out of cell
What are functions of organelle membrane
Separates from rest of cell
Different environments different reactions
Surface area for reactions to occur on
Isolates enzymes
What’s function of a membrane protein
Help in movement of ions or molecules Cell recognition Act as receptors Help adhere to cells Structural support
What’s simple diffusion
Diffusion not requiring energy in form ATP
Movement of non polar or lipid soluble molecules across bilayer
What is osmosis
The net movement of water from area or region of high water potential to region of low water potential through selectively permeable membrane
What is water potential
The potential of water to move across a semi permeable membrane, pressure of molecules
What is the role of active transport in the ileum
Prevents dynamic equilibrium being met
All glucose and amino acids absorbed
Na+ and k+ pump to maintain na+ conc grad
What is the role of diffusion in absorption
Maintain conc grad as cells use up glucose in blood
Glucose molecules move down conc grad into blood
Higher conc of glucose and amino acids in ileum so creates conc grad to blood
What is the reason for cholesterol in the plasma membrane
Adds strength
Keeps it less fluid but not rigid
Pulls hydrophobic tails together
What’s the function of gylcolipids in plasma membrane
Cell recognition
Helps adhere to other cells
Cell surface receptors
Stability
What’s the role of glycoproteins in plasma membrane
Cell recognition
Cell receptor
adhere
What’s facilitated diffusion
The movement of polar molecules down conc grad using carrier or channel proteins
What’s passive diffusion
Diffusion that doesn’t need energy eg facilitated and simple
Why is the plasma membrane called fluid mosaic
Fluid-contents constantly moving
Mosaic-proteins are randomly embedded and shaped
How does channel protein work
Ion or molecule bind to receptor
Channel opens, filled with water so polar molecules can dissolve
How does carrier protein work
Ion molecules binds to protein, causes it to change shape which releases it to other side
Facts about water potential
Closer to 0 the higher the potential
The higher the potential the less solutes in it
What happens to a cell when it’s put in a hypotonic solution
Animal Cell undergoes lysis
Plant cells swell and become turgid and no more water can enter
What is a hypotonic solution
Solution has a higher water potential than cell
What is a hypertonic solution
Has a lower water potential than cell
What happens to a cell in a hypertonic solution?
Animal cell will shrink and shrivel up
Plant cells protoplasm will pull away from cell wall cell is plasmolyzed
What happens to a cell in between plasmolyzed and turgid?
Incipient plasmolyzed or flaccid
How does co transport of glucose and na+ work
Na+ diffuses down conc gradient, the energy from this moves glucose against its gradient
Na+/k+ pump maintains na+ conc grad
What increases rate of absorption/movement across the ileum
Villi, microvilli increases surface area
Increased number of protein channels/carriers
What is large latent heat of vapourisation
Large increase in energy is needed to turn into vapour
Creates large cooling effect
What is large latent heat of fusion
A lot of energy needed to be lost to freeze
Insides/contents of cells will never freeze
What is a metabolite
What is a solvent
Metabolite-involved in chemical reactions
Solvent-what solutes (ionic or polar substances) dissolve in, transports nutrients
What is high specific heat capacity
A large amount of energy needed to increase temperature due to being extensive,y hydrogen bonded
Thermostable environment
What are characteristics of fatty acids
Insoluble/immiscible in water
Soluble in organic solvents
What is polymerisation
Joining of 2 amino acids in condensation reaction to form a peptide bond
What forms of glucose are needed to form
Maltose
Sucrose
Lactose
A glucose + A glucose
A glucose + Bfructose
Bgalactose + A glucose
What’s a hydrolysis reaction
What’s a condensation reaction
Addition of water to break up chains
Removal of water to make chains
What is the test for starch
Iodine solution goes black/blu
What’s the structure of amylose and amylopectin
AMYLOSE
A glucose,Helix,OH on inside,Insoluble, 1,4 glycosidic bonding
AMYLOPECTIN
14 & 16 glycosidic bonding, very branched, helix
What was the test for reducing sugars
Add Benedictus solution
Boil
Goes brick red if reducing sugar
Give examples of reducing and non reducing sugars
Reducing: all mono saccharides most disaccharides
Non reducing: sucrose
What’s the test for non reducing sugars
Heat with HCL
Then add Benedicts
What does a competitive inhibitor do?
It binds with the active site and occupies it Prevents substrate binding with enzyme Less E-S complex’s Less successful collisions Slower rate reaction
What does a non competitive inhibitor do?
Binds to allosteric site Binding changes charges in active site Enzyme denatured Substrate no longer fits Less E-S complexes made Less successful, collisions, slower rate of reaction
What’s needed for enzyme to work
What are attractive forces
Substrate to fit
Physical contact
Pressure put in substrate to break and reform bonds to make products.
What’s the difference between lock and key model and induced fit model
Lock and key: suggests enzyme is one specific shape
Induced fit: suggests active site is a generic shape and moods around substrate
What are characteristics of lipids
Made of carbon, nitrogen, oxygen
Soluble in other organic solvents eg alcohol
Insoluble in water
What are the characteristics of saturated and unsaturated fatty acids
Saturated:fit closely together, solid at room temp, high melting point, regular pattern, strong inter molecular forces
Explain reducing sugar tests
Soluble blue Cu2+ ions reduced by anomeric carbons to Cu+
Cu+ ions form a brick red precipitate in presences of alkaline solution
Characteristics of glycogen
Alpha glucose
Found in liver or muscle cells
1,6 bonding-shorter chains but extremely branched
Small granules
What’s an anobolic and catabolic reaction
Anobolic: making/forming complex molecules
Catabolic: breaking down of molecules
What are triglycerides made of?
What bond forms and how?
3 fatty acids combined with glycerol
Condensation reactions forms 3 Ester bonds to release 3 water molecules
Ester bond
What are proteins made of?
Amino acids-hydrogen, oxygen, nitrogen, carbon, sulfur
What’s starch made of
Amylose and amylopectin which are made of alpha glucose
What are the types of proteins
Globular Fibrous
Haemoglobin. Collagen.
Ball shape Stable and strong
Compact Long chains
Enzymes Cross bridging
Soluble in water
What are polymers, monomers
Monomer-individual building block
Polymer-2 or more joined
What are the roles of proteins
Hormones Enzymes Anti bodies Cell membrane Structural - collagen
What’s the test of lipids
Emulsion test- dissolve in ethanol and shake, then add in cold water
What are phospholipids
2 fatty acids, phosphate and glycerol
What’s a bilayer
Made of phospholipids
Heads associate together and with water
Holds membrane together
Heads face out, tails inside
Hydrophobic Barrie
What are the roles of lipids
Protection Insulation Source of energy Waterproofing Cell membrane
What’s a monosaccharide
Single building block of carbohydrates
What are the functions of carbohydrates
Structural-cellulose cell walls
Energy source-starch glycogen
What’s a disaccharide?
What reaction
Two monosaccharides joined together by glycosidic bonds formed in a condensation reaction
What are amino acids?
What bond?
What’s its structure?
Building blocks of proteins, peptide bonds
Amino group - r group - carboxyl group
How is energy gotten from starch and glycogen
Hydrolysis at ends of chains
Very compact lots stored in small place
Very branched so easy access, quick release
What’s the structure of cellulose?
Parallel chains of b glucose hydrogen bond
Form microfibrils
Microfibres bond to form macrofibrils
Macrofibrils cross bridging to form cellulose
What’s an anomeric Carbon
What’s a reducing agent
The reducing agent of a sugar-bonded to two oxygens
Gives electrons to something else
What are the factors affecting enzyme action
Ph
Temp
Substrate conc
Enzyme conc
What does an inhibitor do
It directly or indirectly interferes with the functioning of the active site of an enzyme
Less E-S complexes made
Less successful Collisions
Rate of reaction slows
What is activation energy
Min amount of energy required to start a reaction
Enzymes lower activation energy
Reactions take place at lower temp
What does polar mean
Uneven distribution of charges across molecule
Oxygen is more electromagnetic so pulls electrons to it
What is cohesion
What is adhesion
Hydrogen bonds between water molecules between slight negative and slightly positive hydrogen and oxygen
What is infection
What is immunity
Infection: interaction between pathogen and body’s defence mechanisms
Immunity: means by which the body protects itself from infection
What defence mechanisms does the body have
Non specific. Specific
Physical barriers phagocytosis Cell mediated. Humoral response
How does the body recognise self material
In fetes, lymphocytes constantly collide with cells
Infections are rare so only encounters self material
If lymphocytes have receptors that fit those of the bodies they undergo apoptosis or are suppressed
What is phagocytosis
Secondary line of defence
1-Pathogens release chemical products which attract phagocyte
2-receptors of cell surface membrane of phagocyte recognise and bind to proteins on surface of pathogen
3-phagocyte engulfs pathogen by endocytosis to form a vesicles inside called phagosome
4-lysosome moves toward phagosome, fuse with it to form phagolysosome
5-lysosomes release their lysozymes, they hydrolyse the pathogens Cell walls
6-products broken down and are either absorbed into cytoplasm or expelled by exocytosis
What is the first line defence
What’s second line defence
What’s third line defence
1-physical barrier eg skin
2-phagocytes
3-Cell mediated and humoral response
What’s an antigen
Proteins that are part of cell surface membrane of organism or substance that’s recognised as non self by immune system and stimulates an immune response
What are lymphocytes
Specific immune response
Type of white blood cell
Produced by stem cells in bone marrow
Two types: B-lymphocytes and T-lymphocytes
What is cell mediated immunity
1-pathogen engulfed by phagocyte, hydrolysed. Pathogens antigen is presented on a MHC complex
2-T cell that has complimentary receptors to antigen bind to it (colonial selection)
3-Creates activation energy which activates clonal expansion of T cell
5-memory cells
-t helper cells
-tcells that stimulate phagocytosis
-tc cells-cytotoxic killer t cells
What does a cytotoxic killer T cell do
Kills abnormal cells that are infected by pathogens
Produces performing which makes holes in cell surface membranes
Cell membranes become freely permeable to all substances, water moves in and bursts cell
What is humoral immunity
1-B cell that’s complimentary (clonal selection) to antigen engulfs pathogen by endocytosis and presents antigen on a MHC complex
2-t helper cell binds to antigen, activation energy, stimulates B cell to divide and clone itself (colonial expansion)
3-memory cells
-plasma cells which produce monoclonal antibodies which are complimentary to antigen
What is the structure of an antibody
4 polypeptide chains, 2 heavy and 2 light chains
Variable region is the antigen antibody complex
Constant region is the rest of antibody
How do antibodies lead to destruction of pathogens
- Mark pathogen by binding to antigen so phagocytes can destroy easier
- agglutination of cells (clumps so easier to be located)
- combine with toxins (prevent them from entering cells)
- attach to flagelum (stop moving easily)
- combine with toxins neutralising them
- lysis if bacterial cells (“punch” holes in cell wall)
How can antibodies be used in medical treatments
Direct monoclonal therapy
- monoclonal specific to antigens on cancer cell produced
- given to patient and they attach to receptors on cancer cells
- attach to surface and block chemical signals that stimulate their uncontrolled growth
- herceptin
Indirect therapy
- radioactive drug or cytotoxic drug attached to antibody
- when it attached to cancer cell it kills them
How are antibodies used in pregnancy testing
HCG produced by pregnant women
1-urine travels up to first zone, HCG acts as substrate and binds to the mobile HCG antibodies that have a blue latex bead attached, form HCG antibody complex
2-urine travels to second zone, where immobile antibody is, binds with HCG antibody complex, blue beads appear a line if pregnant
3-if not pregnant no HCG so beads are swept past zones to the 3rd zone where bond to immobilised antibodies in control window
What’s passive immunity
Introduction of antibodies into individuals from outside source. No direct contact with pathogen or antigen needed. Immunity acquired immediately.
No lasting effect, no memory cells no new antibodies - eg anti venom
What’s active immunity
Natural - individual infected by disease under normal circumstances, body produces own antibodies
Artificial- basis of vaccination, induced immune response without individual suffering symptoms of disease
How does HIV replicate
- Travels in blood stream
- attachment proteins in HIV readily bind to CD4 protein on t helper cell
- lipid envelope fuses with cell surface membrane
- capsid release contents
- hiv reverse transcriptase converts RNA to dna
- viral dna moves into nucleus via nuclear pore and is inserted to dna
- viral dna creates messenger dna which contains instructions for production of viral contents
- hiv particles made by ribosomes move to surface of t helper cell, then bud off using t helper cells surface membrane as their own
How is aids caused
HIV kills or interferes with functioning of t helper cells
T helper cells can’t stimulate B cells
Adequate immune response not produced
How do you work out SA:volume ratio
SA
———— == x:1
Volume
What materials are exchanged by organisms
Respiratory gases
Nutrients
Excretory products
Heat
Examples of passive exchange and active exchange
osmosis and diffusion
Active transport
Features of specialised exchange surfaces
Large SA: volume
Very thin, short diffusion pathway,
Selectively permeable membrane
Movement of environmental medium to maintain diffusion conc
Transport system to ensure movement of internal to maintain conc grad
What mechanisms do insects have for gas exchange
Spiracles
Internal network of tracheae which are supported by strentghened rings prevent collapsing
Tracheoles which extend out through all tissues
Short diffusion pathway for cells to tracheoles
Why are ends of tracheoles filled with water
During major activity muscle cells respire anaerobicslly
Produce lactate
Lowes water potential of cells
Water moves from tracheoles into cells by osmosis taking dissolved gases with it
Volume water decrease, draws in more air
What’s the structure of gills
Gill filaments are stacked
Gill lamella line filaments at right angles increasing surface area of gills
Water taken in through mouth over gills and out the operculum
Counter flow of water to blood
What are the adaptations of leaves for rapid diffusion
Many stomata on underside
No cell far from stomata
Diffusion pathway short
Lots of air spaces in side, inter connecting air spaces throughout mesophyll, gases readily come into contract with mesophyll cells
Larger SA of mesophyll cells rapid diffusion
How do guard cells control opening of stomata
In photophosphorylation, atp produced
Atp powers pumps that cause active tranpsport of k+ into guard guards
This lowers water potential so water moves in by osmosis, causing cells to swell and expand, as guard cells have thicker inside cell wall they bend creating gap in middle
How is water loss limited in insects
Small sa : volume ratio
Waterproof covering - waxy cuticle
Spiracles close during periods of rest
How are plants adapted to restricted water supply
Thick waxy cuticle - less water lost
Rolled leaves-stomata inside, still air, saturated with water, no gradient so water doesn’t move out
Hair leaves “. “
Reduced sa : volume ratio
What structures make up the human gas exchange system
Trachea - rings of cartilage prevent collapsing
Lungs - rib cage protects them
Bronchi - produce mucus to trap dirt, ciliated walls
Bronchioles- lined with epithelial cells, walls of muscle
Alveoli - collagen and elastic fibres, one cell thick
What happens in inhalation
1- external intercostal muscles contract, internal intercostal muscles relax
2-rib cage pulled upwards and out, increasing volume of thorax
3- diaphragm muscle contracts causing it to flatten further increasing volume of thorax
4-increase of volume decreases pressure, pressure inside is less than atmospheric pressure, air is forced inwards down its pressure gradient
What’s the equation for pulmonary ventilation
Tidal volume x breathing rate
Where does gas exchange in humans occur
On epithelial cells of alveoli
How is human system adapted for efficient gas exchange
Alveolar walls one cell thick-short diffusion pathway
Network of capillaries which are one endothelial cell thick
Narrow capillaries-red blood cells pushed against wall short diffusion pathway
Large SA of alveoli-large area for diffusion
Constant ventilation of blood and air, maintain conc gradient
What is the digestive system
Long muscular tube and associated glands
Hydrolyse large insoluble molecules into smaller soluble ones
What happens in each of the following Oesophagus Stomach Ileum Large intestine Salivary glands
O-peristalsis to push food bolus from mouth to stomach
S-muscular sac, stores and digests food eg proteins
I-further food absorption and digestion, enzymes produced by pancreas secrete into ileum, super folded walls
L-absorption of water and storage of faeces
SG-near mouth and produces salivary amylase
What are the two stages of digestion
1-physical breakdown
By teeth creating larger SA for enzymes
Churned by muscles in stomach
2-chemical digestion’s
Enzymes hydrolyse insoluble molecules carbohydrase, lipase, protease
What are the stages of carbohydrate digestion
Saliva enters mouth from salivary glands and is mixed with food through chewing
Saliva contains salivary amylase, starts hydrolysing starch into maltose
Food swallowed and enters stomach, amylase denatured
In Duodenum mixed with pancreatic juices-pancreatic amylase continues to hydrolyse. Bile neutralises acidic stomach conditions
Muscles in intestine wall push food into ileum, membrane bound maltase in epithelial membrane breaks maltose down into glucose
What happens in lipid digestion
Small intestine broken down into micelles by bile
Lipids are emulsified
Lipase enzymes in pancreatic juices hydrolyse Ester binds to form fatty acids and glycerol
What happens in protein digestion
Peptidases hydrolyse proteins into amino acids
- endopeptidases hydrolyse central peptide binds forming shorter chains
- exopeptidases in hydrolyse terminal peptide bomds to form dipeptides and monopeptidee
- dipeptidases hydrolyse bonds between dipeptides, membrane bound enzyme in ileum
Features of transport systems
Suitable medium to carry materials in normally liquid based
Form of mass transport
Closed system of tubular vessels
Mechanism of transporting medium within vessels
Achieved by
Animals :muscle contraction
Plants : natural passive movements
What type of circulatory system do mammals have
Closed, double circulatory system as when passed through lungs it loses pressure and needs higher pressure to get around whole body
Where does blood from right atrium go to
Through atrioventricular valve into ventricle, then out the pulmonary artery to lungs, then to pulmonary vein to left atrium, through atrioventricular valve to ventricle then up out aorta to body
How does the heart get blood
Coronary arteries
What happens in cardiac cycle
1- diastole
-blood returns to heart, atria relaxed, as they fill pressure builds once bigger than pressure below in ventricles, atrio valve opens
-blood passage aided by gravity
2-atrial systole
-contraction of Atria along with recoil or relaxed ventricle walls forces remaining blood into ventricles
3-ventricular systole
-short delay, walls contract simultaneously
-increase pressure so it’s higher within them than in atria, forces shut atrio valves, pressure increase more so it’s higher than artery and aorta
-opens semi lunar valves and then contraction forces blood out ventricles.
