Study- Term 1 Flashcards
Prokaryotes
Unicellular, DNA arranged plasmid, no nucleus or membrane bound organelles
Eukaryotes
Multi cellular,plants, fungi, animals, protests, can have special functions, has a true nucleus and has a membrane bound organelles
Both Eukaryotes and prokaryotes
Ribosomes, genetic material, cytoplasm, cell membrane
Cell requirements for survival
Energy sources (light or chemical)
Matter (gases such as carbon dioxide and oxygen)
Removal of wastes
Simple nutrients (monosaccharides, disaccharides, polysaccharides)
Light (photosynthesis)
Energy comes from the sun in the form of light
Photosynthesis uses light energy to synthesise organic nutrients (chemical energy)
Chemical (chemosynthesis)
Energy is released from a chemical reaction
Exclusively used by prokaryotes-organisms found in extreme environments. E.g., deep sea
Matter
- Carbon dioxide is needed for photosynthesis in order to create energy
- oxygen is needed for cellular respiration in order to create energy
Carbohydrates
Important energy sources
Monosaccharides 
Carbohydrate monomers (monomer= a molecule that can be bonded to are the identical molecules to form a polymer)
Disaccharides 
Formed from two monosaccharides
Polysaccharides
Many monosaccharides joined together
Removal of waste
Cells need to remove the waste products so that they do not reach toxic levels within the cell interfering with chemical reactions or damaging the cell
Endosymbiotic theory
Eukaryotes were formed when a bacterial cell was ingested by a larger bacterial cell to become the organelles inside
Organelles
A small cellular structure that perform specific functions for the cell as a whole
Phospholipid bilayer
The main structure of the cell membrane consisting of two layers of phospholipids arranged so that the hydrophilic heads face the internal and external fluid environments
Protein Channel
A channel passing through the centre of a protein (integral proteins or between adjacent protein molecules) the lining in which is hydrophilic it allows water soluble substances to pass through the cell membrane and into or out of the cell
Glycoproteins
A protein that has branching Carbohydrate chains on their free surfaces the carbohydrate chains act as important recognition sites
Cholesterol
Cholesterol is found between the phospholipid molecules in the bilayer it has hydrophobic and hydrophilic portions it regulates the fluidity of the membrane so that it is neither too rigid nor to fluid for the functioning of the cell
The cell membrane
A selectively permeable barrier-controls movement of substances into and out of the cell
Selectively permeable
Small substances diffuse through easily large substances cannot move through
Hydrophilic and hydrophobic
Hydrophilic is water loving head hydrophobic is water hating tail
Passive transport
- Does not require energy
- Diffusion is simple and facilitated -osmosis
- Goes with the concentration gradient (high to low)
Active transport
-Requires energy in the form of ATP
-Endocytosis
-Phagocytosis
-Exocytosis
-Goes against the concentration gradient( low to high)
Solute
Substance dissolved in another substance E.g.salt 
Solvent
A liquid that dissolves a substance E.g., water
Solute + solvent=solution
Simple diffusion
- Free unaided movement of small hydrophobic molecules or ions
- from an area of high solute to low solute concentration
- as a concentration of molecules become equal either side of membrane, cell reaches dynamic equilibrium
- Number of molecules entering = Number of molecules leaving
Facilitated diffusion
- Larger or hydrophilic molecules are carried from a high solute to a low solute concentration across the cell membrane by transport (integral) proteins (channel proteins and carrier proteins)
- no energy is required
Active transport
- Transport of molecules or ions across a membrane against a concentration gradient by use of energy usually ATP
- molecules go from low to high solute concentration
ATP
- Molecule that stores and transfers energy in cells
- Energy is needed because the substance must be moved against its natural tendency to go from high to low solute concentration 
Endocytosis
-Active transport of materials into cells
-two main types:
—>Phagocytosis: cell eating- The membrane fuses around the particle and forms a vessel of food vacuole that becomes incorporated into the cytoplasm
—> pinocytosis: cell drinking
Exocytosis
- Active transport of materials out of the cells
- Materials are pushed against the cell membrane and then opens up to external environment to expel the contents
Osmosis
- Movement of water molecules across a selectively permeable membrane
- from low to high solute concentration
Osmotic potential
The ability of a solution to lose water molecules across a semipermeable membrane
Hypertonic solution
- More solute molecules outside the cell which causes the water to be drawn out of the cell
- ‘ Plazmolysed’ the process in which cells lose water in a hypertonic solution
Hypotonic solution
- Less solute molecules outside the cell water will move into the cell
- cell will swell and become turgid
Isotonic solution
The concentration of solute is equal on both sides
Factors that affect movement of material across cell membranes
Temperature particle size concentration osmotic potential SA:V ratio
Temperature affect on movement
Molecules move faster at high temperatures diffusion occurs faster at high temps
Particle size affect on movement
Small molecules require less energy to move smaller particles will diffuse faster than larger particles
Concentration effect on movement
The greater the difference in concentration between the two locations the faster diffusion will occur
Osmotic potential effect on movement
If the osmotic potential is low there will be a net flow of water into the cell by osmosis if it is high there will be a net flow of water out of the cell by osmosis in an isotonic solution the same amount of water leaves the cell as it enters
SA:V ratio
Smaller cells with higher SA:V ratio diffuse quicker more efficiently than larger cells with smaller SA:V ratio
Metabolism
Chemical reactions occurring in cells are known as metabolism
Anabolism
Synthetic reactions (build up of molecules)
Catabolism
Breakdown reactions (large molecules into small molecules) Catabolism + anabolism = metabolism
Factors affecting metabolism
- Molecules only react when they collide
- By increasing frequency of collision will increase the speed of reaction
1. Concentration of substance
2. Temperature
3. Increasing surface area of the reaction site
4. Presence of a catalyst
Enzymes
Enzymes are globular proteins that lower the activation energy needed for a chemical reaction to take place they speed up the actual rate of the reaction without being used up or consumed and therefore can be reused
Enzymes are
- Specific so they assist in one specific part of reaction
- required in small quantities as they can be reused
- do not alter the end products nature it only speeds up the reaction
Substrate
The substance the enzyme works on
Products
The substance produced at the end of the reaction
Induced fit hypothesis
The substrate does not always fit precisely into the active site of the enzyme
- both the enzyme and substrate are modified so that a better fit between the two is induced
- this process distorts the substrate and can lower the activation energy for a chemical reaction
Activation energy
The energy needed to start a chemical reaction
Factors affecting enzyme activity
If conditions are too high the enzymes denature
if conditions are too low the enzymes don’t activate
Photosynthesis
Carbon dioxide + water —> glucose+ oxygen
Synthesise
The building up of complex molecules from simpler substances requires energy and enzymes
Chlorophyll
Allows energy in the sunlight to drive chemical reactions (green pigment)
Chloroplasts
Acts as energy transducers, converting light energy into chemical energy. Can be found in chlorophyll
Energy transducers
Allows light energy into chemical energy
Starch
Is a glucose produced that is stored in the plant cell
Photosynthesis
The process in which light energy, trapped by chlorophyll is used to convert carbon dioxide abs water into glucose and oxygen cells
To photosynthesise a leaf needs
- A method for gas exchange
- A way to deliver water
- To remove glucose to other parts of plant
- efficient means of absorbing light energy
Waxy cuticle
Reduce water loss
Upper epidermis
One Cell thick and transparent to allow light energy
Palisade mesophyll
- Contain chloroplasts
- Cells densely packaged to maximise light absorption
Vein
- Xylem delivers water
- phloem—> food
Spongy mesophyll
Loosely package cells covered in water and air spaces around them aid diffusion of gases
Leaf blade
large surface area and thin
Leaf stalk
Holds leave in the best position to receive the light
Stomato
Allows entry of carbon dioxide and exit of oxygen
Specialised cells
Cells that have specific function
Most specialised cells will form the building blocks of complex tissues and organs.
Red blood cells
Contains haemoglobin for oxygen transport
White blood cells
Contains powerful enzymes to digest bacteria
Cell lining bronchioles
Has cilia to trap and remove mucus and dust particles
Motor nerve cell
Elongated, and transmits information the central nervous system to a muscle
Palisade cell
Contains many chloroplasts
Root hair cell
Has long extension to increase surface area for absorption of minerals and water
Phloem sieve tube
Transports sugars through the body of a plant
Sperm cell
Carries male parent’s genetic information ready for fertilisation
Egg cell
Carries female parent’s genetic information, and has food stores in cytoplasm
Cell Differentiation
Cell differentiation is the process by which unspecialised cells, called stem cells, become specialised cells.
Stem cells
Stem cells are unspecialised cells that can reproduce themselves indefinitely.
They have the ability to differentiate into many different and specialised cell types.
This occurs when a damaged cell needs to be replaced or repaired with an equally specialised cell
Totipotent
Embro, Can differentiate into all cells, easy isolate and grow, unlimited self renewal, high risk of tissue rejection, ethical issues, teratoma formation
Pluripotent
Blastocyst, umbilical cord, Differentiate into cells derived from 3 germ layers, Easy to isolate and grow, unlimited self renewal, High risk of tissue rejection, ethical issues, teratoma formation
Multipotent
Organs with specialised tissues, Differentiate into special lineage of cells, Less likelihood of tissue rejection, less ethical issues, Hard to isolate, limited differentiation
General Stem Cell Function
Unspecialised cells that can reproduce themselves indefinitely. They have the ability to differentiate into many different and specialised cell types.
Gaseous exchange
The transfer of gases between an organism and the external environment in either direction, occurs by diffusion, includes the exchange of oxygen and carbon dioxide in respiration and photosynthesis
Types of gas exchange systems in animals
Integumentary
Gills
Tracheal
Lungs
Integumentary
Occurs through the skin
E.g, earthworms and amphibians
Gills
Exchange of gases in water environments e.g, fish
Tracheal
A network of small tubes that carries oxygen to the entire body. Independent of it circulatory system e.g, insects
Lungs
Exchange of gases within the body. Gas is circulated by the cardiovascular system e.g, humans, birds-different air sac structure
Things animals have in common to maximise gas exchange
Large SA
good blood supply
Concentration gradient
Structural features of gas exchange
Thin Large SA Moist Concentration gradient Blood supply
Thin
Short diffusion distance allows diffusion to occur at a faster rate
Large SA:V ratio
Large surface area (SA:V)
Many alveoli are present in the lungs with a shape that further increases surface area
Moist
Gases dissolve in the moisture helping them to pass across the gas exchange surface
Concentration gradient
The air in the lungs has a higher concentration of oxygen then that of the oxygen depleted blood and a lower concentration of carbon dioxide
Blood supply
Ensuring oxygen rich blood is taken away from the lungs and carbon dioxide rich blood is taken to the lungs
Circulatory system
The thin porous walls of the capillary allows substance to pass in and out of circulatory system
High SA:V Ratio
Exchange between blood plasma and extra cellular fluid occurs via diffusion and filtration across capillary walls
Circulatory system
Humans have a closed circulatory system. The blood is enclosed within a system of blood vessels and the heart This system includes: -A multi chambered heart -Blood vessels -Blood
Double circulatory system
Blood passes through the heart twice via two sequential pathways:
- Pulmonary circulation
- Systemic circulation
Blood vessels
Responsible for transporting blood throughout the circulatory system
Veins
Epithelial layer of cells, an elastic layer, muscle walls and connective tissue, thinner than arteries, blood transport to the heart, deoxygenated, has valves
Capillaries
Single layer of epithelial cells, very thin, connect arteries to veins, deliver nutrients and other substances to extra cellular fluids, and receive waste, site of exchange of materials e.g, gases connects arteries to veins, no valves
Arteries
Same structure as veins but thicker muscular walls, blood transports away from the heart, oxygenated, no valves
Valves
Make blood go in one direction
Exchange of materials
The structure of capillaries enables the exchange of material between the circulatory system and extra cellular fluid (body fluid outside the cells)
Exchange materials include
Oxygen, carbon dioxide, water, nutrients and ions
Filtration occurs because of two opposing forces: hydrostatic (blood pressure), osmotic pressure
This pressure form these two forces pushes fluid into and out of the capillaries
How is exchange and transport of oxygen and carbon dioxide possible
The coordination between the circulatory and respiratory system
Gas exchange
Occurs in the capillaries
Occur at the alveoli or in the body tissue
Structure of alveoli
Very thin walls, cup shaped, surrounded by networks of blood vessels called the capillaries
Respiratory system step 1 to step 5
- Oxygen enters the respiratory system and moves into the alveoli
- The concentration of oxygen in the alveoli is greater than that of the surrounding capillaries
- Due to this concentration difference oxygen is able to diffuse into the capillary and carbon dioxide is able to diffuse into the alveoli as the blood moves past
- Carbon dioxide is exhaled
- A similar process occurs during gas exchange in the the body tissues
Digestive system
Converting food into the simplest form in order for them to be absorbed and carried to our body cells
Our diet consists of three types of molecules:
Carbohydrates, proteins, fats
The process of digestion can occur mechanically or chemically
4 components of digestive system
- gastrointestinal tract
- pancreas,gallbladder,liver
- enzymes,nerves,blood,hormones
- mesentery
Function/structure of villi
Creates huge SA to maximise absorption
Chemical digestion
The process of breaking apart complex molecules into simple molecules
Digestive enzymes
Enzymes are essential to digestion as they increase the rate of breakdown of food molecules
The effect of pH on enzyme activity
Digestive enzymes are sensitive to change in PH and will function optimally at a certain pH level
different types of enzymes will function optimally at different pH ranges
Digestive enzymes
Amylase
Protease
Lipase
Absorption
The passage of digested substance from the digestive tract into the circulatory and lymphatic systems for delivery to cells
Structure of the ileum
The ileum is very long, this provides food with enough time for absorption to occur
-covered in small finger like projections called villi which greatly increase the surface area of the absorption site
Xylem
Water and minerals
No end walls between cells
one way only
Outer cells are not living
Phloem
Organic molecules and
End walls (sieve plates)
Two way movement
cells are living but needs support
Xylem and phloem both
Transport things in plants
