Bio Cells

Passive transport

Passive transport is the movement of substances that does not require energy as it is moving against the concentration gradient (from high to low)

Active transport

• Active transport is transport that requires energy (ATP) to move substances across the plasma membrane as it is moving substances from a low to a high concentration (against the concentration gradient)

diffusion

•  diffusion is the movement of substances from a high to a low concentration gradient and therefore requires no energy. 

Facillitated diffusion

• Facilitated diffusion is the diffusion of substances through carrier proteins or transport proteins in the plasma membrane. It is a passive process because substances move down their concentration gradient. 

Osmosis

• Osmosis is the movement of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration.

Cytosis

• –An active transport process which transports large amounts of substances across the membrane. Endocytosis is into the cell and Exocytosis is out of the cell. 

Plasma membrane

• - A plasma membrane is a semi-permeable phospholipid bilayer. It separates the interior of the cell from the external environment, and controls the transport of substances into and out of the cell. 

Concentration gradient

•  A concentration gradient is when there is a difference in the particle concentration of a substance between two areas.

Enzyme

• Enzymes are proteins that act as biological catalysts to increase the rate of reactions by decreasing the activation energy required for the reaction.

Active site

• The part of the enzyme that the substrate binds to, it is specific to a substrate. 

Denaturing

• When the bonds in an enzyme break which changes the shape of the active site so the substrate can no longer bind to it.

Inhibitors

•  slow or stop reactions

Cofactors

• factor needed for enzyme to work by changing shape / fitting into active site

Photosynthesis

•  Photosynthesis is a series of enzyme controlled chemical reactions in the chloroplasts of plant cells that uses light energy absorbed by chlorophyll to combine carbon dioxide with water to make glucose.

Mitosis

•  Mitosis is the process where a body (somatic) cell divides for growth and repair, producing identical cells. 

Semiconservative DNA

replication is when the original DNA is used to make a new copy of DNA. The two copies of DNA produced each contain one of the original strands and a new copied strand

Respiration

Anaerobic repiration

•  Glucose is broken down into lactic acid and ATP (energy); no oxygen is present, therefore less energy (2 ATP) is produced

Functions of the plasma membrane

• gives the cell structure

• semi permable barrier control what enters and exits the cell.

• communication with other cells-cell signalling

• recognises foreign substances

• allows mobility in some organisms

• provides a site for various chemical reactions to take place

Hyper tonic, hypotonic and isotonic

• a hypertomic solution has a higher concentration of solute particles dissolve in it and therefore lower water potential.

• a hypotonic solution has a lower concentration of solute particles and therefore higher water potential.

• isotonic solutions have an equal concentration of solutes and therefore equal water potential.

carrier protiens

carrier proteins must use energy to transport substances agianst the concentration gradient.

Factors that affect the rate of transport of substances

• Surface area to volume ratio of the cell, a larger surface area to volume ration is faster transport a large surface area allows more particles to be transported across a membrane at any one time and a small volume makes sure the distance particles have time to diffuse across once inside the cell is kept short/small and therefore remains efficient.

• Temperature, higher temp faster transport because particles are moving at a faster rate.

• Distance, long distance is slower diffusion becomes to inefficient

• Size of concentration gradient, big difference between the two areas = steep/large concentration gradient = fast diffusion

• Size of particles, large particles diffuse slower than small particles

Cells adapted or efficient transport:

Cells adapted for efficient transport will be small or have a long thin shape, or have outer folds of the plasma membrane so they can maintain a large surface area to volume ratio, so that diffusion of substances remains efficient and therefore they can carry out reactions of life processes successfully.

Cells adaptations for active transport

• Cells that carry out a lot of active transport will be cells that must transport a lot of substances against their concentration gradients such as nerve cells and muscle cells that use sodium/potassium pumps a lot, or that must use a lot of cytosis such as white blood cells.

• These cells will have more mitochondria to carry out more respiration to provide the ATP/energy needed for the active transport. They will also have more carrier proteins in their plasma membrane to carry the substances against their concentration gradients across the plasma membrane.

factors that effect mitosis: stage of life

• stage of life, cells need to be rapidly dividing to enable growth. Therefore, there is an increased rate of mitosis.

• This includes, infancy and childhood in animals and germination in new seasons.

• Damage to cells or tissue will increase the rate of mitosis.

factors that effect mitosis: location of cells

• skin cells and the lining of the intestinal tract need to be rapidly replaced, therefore more mitosis occurs.

• In cells that do not indergo as much wear and tear such as liver cells and muscles cells of the intestines mitosis is not frequent.

• in plants the tip of roots and shoots are continually growing and therefore more mitosis.

Factors that effect mitosis: enzymes

• Mitosis, and DNA replication that precedes it, both involve enzymes 

• so factors that affect enzyme activity will affect the rate of mitosis i.e. temperature, substrate (reactant) concentration, co-enzymes and poisons, nutrient availability, pH

factors that effect mitosis: nutrient and energy available

• In order to build new DNA and create new cells, essential nutrients need to be available. Therefore, in the absence of essential nutrients, mitosis and DNA replication slow down/stop. 

define mitosis

• Mitosis is the process where a somatic cell (body cell or non-sex cell) divides for growth and repair

purpose of mitosis

• The purpose of mitosis is to produce new, genetically identical, cells for growth and repair, and to maintain a large surface area to volume ratio of the cell. Maintaining an efficient SA/V ratio for transport.

importance of mitosis

• The significance of mitosis is that it produces two new, genetically identical daughter cells that are able to function the same way as the original parent cell. 

Before mitosis begins

• Interphase is an important part of the cell cycle 

  • DNA replication takes place 

  • Each Chromosome replicates to form two chromatids  

  • Chromosomes are not seen individually – still exist as chromatin material 

  • Two centrosomes are formed by duplication

mitosis phases

1. Prophase – Preparation phase
   
   

2. Metaphase – Move to the middle
   
   

3. Anaphase – Chromatids pulled Apart
   
   

4. Telophase – Two nuclei/cells 

Photosynthesis equation

Water + carbon dioxide → Glucose + oxygen

Aerobic respiration equation

Glucose + oxygen → Energy (36 ATP) + carbon dioxide + water

Anaerobic respiration

Glucose → energy (2 ATP) + lactic acid 

Purpose of DNA replication

to replicate the cells' DNA before cell division/mitosis, so that after cell division, each new cell will have a complete set of identical genetic information. 

process of DNA replication

1) replication fork formation

2) Primer binding

3) ELongation

4) termination

5) DNA coils to double helix

Fork replication

• an enzyme unwinds and unzips the parent DNA strand by breaking hydrogen bond which expose the nucleotides

Primer binding

• An enzyme helps bind primers needed to initiate DNA replication

elongation

An enzyme adds new nucleotides to the DNA strand via complementary base pairing

Termination

• Once both strands are formed, an enzyme removes primers and proofreads.

• Another enzyme joins DNA fragments together.

Why are enzymes so important in DNA replication

• Enzymes are involved in each step of DNA replication, and therefore the rate of DNA replication is dependent on factors affecting enzyme action. Therefore, these factors would also affect growth, repair and cell division/mitosis.
  
  

• If DNA fails to replicate or could not replicate fast enough, it would slow or stop the process of mitosis.
  
  

• Growth and repair of an organism may be seriously affected, resulting in eventual death / negative survival.

Factors effecting DNA replication

• Temperature

• pH

• Substrate concentration

• Enzyme concentration

• Co-factors

• Inhibitors (competitive, non-competitive

Shade tolerant plants adaptations

• Leaves are large - maximise Surface area to receive light

• Leaves positioned horizontally 

• Leaves are thin with few cell layers to allow light penetration at all levels 

• One palisade layer 

• Spongy mesophyll has many chloroplasts 

• Larger chloroplasts 

• Larger range of light absorbing pigments 

Sun tolerant plants adaptations

• Leaves smaller to reduce SA exposed

• Leaves positioned vertically 

• Leaves are thicker with more cell layers as intense light can penetrate

• Some can collapse their leaves to prevent damage 

• Thick waxy cuticle 

• Leaves can be hairy to minimise water loss 

• Two or more palisade layers

• Spongy mesophyll has few chloroplasts 

• Chloroplasts are smaller

• Fewer light absorbing pigments

• More of the enzyme RUBISCO

• Chloroplasts can move easily (cytoplasmic streaming)  

DNA replication define

DNA replication is an enzyme-controlled process, that makes a copy of the double-stranded DNA molecule

DNA replication is semi conservative

DNA replication is semi-conservative, meaning each molecule of DNA that is created contains one new strand and one old strand

 The two newly made strands are identical

Features of chloroplast that help with photosynthesis

1. Thin, semi-permeable double membrane allows light to penetrate through to the thylakoids and it controls the transport of substances in and out of the organelle/chloroplast so that the reactions of photosynthesis can occur

2. Oval/cylindrical shape provides a large surface area to volume ratio for efficient transport of substances in and out of the chloroplast so the reactions of photosynthesis can occur efficiently

3. Clear stroma allows light to reach the thylakoid membranes/grana and contains enzymes so the reactions of photosynthesis can occur efficiently enough

4. Thylakoid membranes stacked into grana contain chlorophyll for absorbing light energy and increase the surface area for light absorption and the light dependent reactions, and therefore increases the rate of photosynthesis

light dependent reactions

Light-dependent reaction takes place in the thylakoid membrane within the chloroplast. Light energy is absorbed by the pigment chlorophyll. This light energy splits the water molecule into oxygen and hydrogen. Hydrogen ‘goes to the’ light-independent process, while oxygen is excreted as a waste product (via stomata on leaves).

Light independent reaction

• Light-independent reaction takes place in the stroma of the chloroplast. The hydrogen is combined with carbon dioxide through a series of reactions to form a glucose molecule.

photosynthesis definition

• hotosynthesis is a series of enzyme controlled chemical reactions that occur in the chloroplasts of plant cells, which use light energy absorbed by chlorophyll drives reactions with carbon dioxide and water to make glucose.

purpose of photosynthesis

The Purpose of Photosynthesis

The purpose of photosynthesis is to produce glucose that can then be used in the process of cellular respiration to produce the energy needed for life processes.

Chloroplasts

The chloroplast is the organelle where photosynthesis occurs in plant cells.

• Chlorophyll absorbs different wavelengths of light 

• Plants are green in colour usually because this wavelength is reflected 

Features that help leaves photosynthesis

Thin, clear, and waterproof cuticle

Palisade cell layer – palisade cells

Spongy mesophyll layer

Stoma (plural stomata)

Guard cells

Root hair cells

• Root hair cells are extensions of the root 

• They themselves have extensions 

• These extensions provide more surface area

• This means that the rate of osmosis can be maximised 

• Water is then pulled up the plant by capillary action via the xylem vessels

• Root cells do not contain chloroplasts because they are not exposed to light and do not need to carry out photosynthesis.

where does anaerobic take eplace

Anaerobic respiration takes place in the cytoplasm of an animal / plant cell.

where does aerobic take place

Aerobic respiration takes place in the mitochondria of an animal / plant cell.

Breakdown of aerobic repiration

tage 1: Glycolysis

• Glucose enters the cell from the bloodstream via facilitated diffusion

• In the cytoplasm of the cell glucose becomes pyruvate

Stage 2: Link Reaction

• Pyruvate moves into mitochondrial matrix

• Pyruvate becomes Acetyl CoA (an enzyme)

Stage 3: Krebs Cycle

• Still in the mitochondrial matrix

• Enzymes convert Acetyl CoA into different chemicals

• This provides electrons for the Electron Transport Chain in the form of NADH

Stage 4: Electron Transport Chain

• Occurs on the cristae of mitochondria

• NADH drops off its electrons to the chain located on the cristae

• The Electron Transport Chain produces lots of ATP via an enzyme called ATP synthase

• ATP synthase makes ATP from ADP and an inorganic phosphate

• Overall 38 ATP are produced via Aerobic Respiration

• Once the electrons have gone through the chain they are accepted by oxygen

Respiration

Respiration is a process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide.

 

The mitchocondria

• A mitochondrion (mitochondria plural) is a membrane-bound organelle present in most animal and plant cells

• Mitochondria are the sites of aerobic (cellular) respiration

• Mitochondria use energy from organic compounds to make ATP

• A mitochondrion (mitochondria plural) is a membrane-bound organelle present in most animal and plant cells

• Mitochondria are the sites of aerobic (cellular) respiration

• Mitochondria use energy from organic compounds to make ATP

. Semi-permeable double membrane

2.Inner membrane that’s folded to form cristae

3.Fluid filled space called the matrix 

4. Oval shape (SA:V)

factors effecting enzymes

• temperature

• pH

• co factors

• substrate concentrate