Biology Year 11 Unit 1 and 2

Cells

Basic unit of structure and function in living organisms. All living matter is composed of cells and products. They arise from pre-existing cells which contain inherited genes. The cell is a functioning unit of life - a self-perpetuating systems.

Fluid Mosaic Model (*General Information)*

Cell membrane is a selectively permeable barrier as some mall substances can move through the membrane very easily.

**Mosaic:** arranges small pieces to make a large piece

**Fluid:** moving around

The chemical structure of the membrane is based on the ‘fluid mosaic model’

Phospholipid Bilayer *(membrane structure)*

Lipid Bilayer acts as the base structure for the cell membrane. Comprises of two layers of phospholipid molecules, each consisting with a hydrophilic head (likes water), and hydrophobic tail (hates water). Glycoproteins, glycolipids, and cholesterol are also an integral part of the membrane structure, contributing particular proteins.

Proteins within the Membrane (organisms)

Integral proteins, peripheral proteins, protein channels, phospholipids, glycoproteins, glycoproteins, glycolipids, cholesterol, carrier proteins, channel proteins

Integral proteins

Necessary - goes into through the membrane

Peripheral proteins

Attached outside of the membrane

Protein channels

Some structural, some act as a carrier transporting specific molecules through the membrane

Phospholipids

Important components of cell membrane

Glycoproteins

Important for cell recognition

Glycolipids

Helping cells to aggregate in the formation of tissues

Cholesterol

Between lipid bilayers, regulates fluidity

Carrier proteins

Specific shape that bind to molecule that cant fit inside the cell

Channel proteins

Inside the channel proteins are hydrophilic and allows water and ions to pass through

Cell specialisation

They turn into any cell in the body

Stem cells

Make all of a certain type of cell

Channel and carrier proteins

Transport of small molecules and ions

Cytosis

Transport of large molecules

Passive transport

Move in and out of cell across plasma membrane, e.g. diffusion and facilitated diffusion, osmosis

Diffusion

High to low concentration trough selectively permeable membrane

Facilitated diffusion

Transport of substrate molecules - like carrier molecules

Osmosis

Diffusion of water across partially permeable membrane

Diffusion cont.

Doesn’t require energy, occurs across a partially permeable membrane, move down concentration gradient, equilibrium occurs when either side of the membrane are equal, movement stops when this occurs

Factors affecting diffusion

Concentration gradient (*diffusion rates are higher when there is greater difference between two regions)*, diffusion distance *(shorter distance is greater rate)*, surface area *(greater rate with large SA)*, physical barriers *(thick barriers slow diffusion, pores enhance)*

Facilitated diffusion

Aided by integral proteins, diffusion selectively increases with specific molecules, no energy required, higher diffusion rate is desirable

Diffusion through channels

Diffuse rapidly by channel mediated diffusion, hydrophilic pores, allows some solutes to pass through, regulates flow of ions by open and closing

Carrier mediated diffusion

Aided across the membrane by transmembrane carrier proteins

Osmosis

Diffusion of water across a partially permeable membrane, greater total of solute concentration

Osmotic pressure

Pressure that needs to be applied to a solution to prevent the invalid flow

Isotonic

Same osmotic pressure as another solution

Hypertonic

Low concentration of water, high concentration of solutes

Hypotonic

High concentration of water, low concentration of solutes

Active transport

Energy (ATP) consuming, two parts - exocytosis and endocytosis, AT move against their concentration gradient, performed by specific carrier proteins

Sodium potassium pumps

Energy from ATP to move hydrogen ions from inside to outside, large difference in proton concentration leaving inside of plasma membrane neg charged

Coupled transport

CO-TRANSPORT, return of sodium down concentration to transport glucose into the intestinal epithelial cells

Chemiosis

Movement of hydrogen ions across membrane to inner membrane, ATP synthase of ADP

Endocytosis

Substances moving into cell, three forms (phagocytosis - *engulfment of solid particles,* pinocytosis - *engulfment of liquid particles,* receptor mediated - *engulfment of specific particles according to membrane receptors)*

Exocytosis

Substances moving outside

Cell size

SA:V highly influenced by the shape of the cell, cells that have folds maximise SA:V ratio

Maximising SA:V and diffusion

Elongating cells, cell extension or hairs, inert vacuole, cytoplasmic streaming, convert molecules to another type

Autotrophs

Make own glucose through photosynthesis

Heterotrophs

Digest other organisms to release flucose

Macromolecules

Polymers build from monomers

Polymer

Long chain molecule built from monomers

Monomers

Molecules that bound to others to form polymers

Types of polymers

Proteins, carbs, nucleic acids

Proteins

Made from amino acids

Carbs

Built from monomers of simple sugars

Nucleic acid

Made of nucleotides, genes made of DNA and nucleic acid - two types, deoxyribonucleic acid DNA, and ribonucleic acid RNA

Functions of polymers

Structural support, storage, transport, cell communication, movement, defence against foreign substances, works with enzymes

Prokaryotic Cells

Cells use food to maintain a stable environment.

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Single celled, lacks a membrane bound nucleus, no nucleus, single cellular chromosome, cell walls containing pephiglycogen, non cellular, tiny, contains no cytoplasm or organelles, no chromosomes (only DNA and RNA), enclosed in protein coat, depends of living cells for metabolism and reproduction via replication

Endosymbiosis

Theory that the first life arose under unique environmental conditions and 4 billion years ago - first 2 main types of pro cells were archaea and bacteria

Eukaryotic cells

Facilitate biochemical processes

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Cells 10-100µm, membrane bound nucleus and organelles, linear chromosomes make up animal, plant, fungi and protists cells

Anabolic reactions

Building up complexity

Catabolic reactions

Breaking down complexity

Enzymes

Speeds up chemical reactions, enzyme binds to its substrate forming an enzyme

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Catalyst speeds up

Enzyme is a catalytic protein

Substrate region enzyme acts upon

Active site where substrate binds

Enzyme structure process

1\.     Enter active site.

2\.     Substrate held in active site of enzyme.

3\.     Enzyme lowers the activation energy for a chemical reaction.

4\.     Substrates are converted into products.

5\.     Products of enzyme are released.

Active site is available for new substrate molecules.

Active site can lower Ea by

Orientating substrates correctly, straining substrate bonds, providing a favourable environment, covalently bonding to substrate

Lock and key

Substrate is the key and active site the lock

Induced fit

Active site influences the shape of substrate

Enzyme inhibitors

Competitive and non competitive

Competitive inhibitors

Bind to active site competing with substrate

Non-competitive inhibitors

Bind to another part of enzyme to change shape making active site less effective

Cell membrane

Controls what comes in and out of cell

Cell wall

Ridged outer layer of plant cell

Cytoplasm

Gel-like fluid where organelles are found

Mitochondria

Produces energy the cell requires

Lysosomes

Uses chemicals to break down food

Vacuoles

Stores food, water, and other materials

Golgi bodies

Post office - receives proteins from ER,m packages, and distribute them

Chloroplasts

Captures energy from sun and produces food in plant cells

Endoplasmic reticulum

Has passageways that carry proteins from one part of the cell to another

Smooth endoplasmic reticulum

Synthesis of lipids, steroid hormones, detoxification of harmful metabolic by products, etc.

Rough endoplasmic reticulum

Produces proteins for rest of cell, contains ribosomes that make proteins

Ribosomes

Assemble amino acids to create proteins

Nucleus

Control centre of cell that contains DNA

Nucleolus

Inside nucleus and produces ribosomesq

Chromatin

Tiny strands inside nucleus directing cell functions

Cell respiration - four main components

Glycolysis, link reaction, krebs cycle, electron transport chain

Cell respiration

Uses glucose and oxygen and produces ATP energy, carbon dioxide and water. Occurs on cell cytoplasm and mitochondria

Glucose + Oxygen – 6Carbon Dioxide + 6Water + ATP (energy)

Photosynthesis

Uses sunlight, water and carbon dioxide to produce glucose and oxygen

Two sections of photosynthesis

Light dependent reactions - *uses sunlight to split water*

Light dependent reactions - *uses CO2 in enzyme reactions to produce glucose*

Respiratory system

Inhalation - *ribs move up and out, diaphragm contracts and moves downwards, lowers air pressure in lungs as volume increases, therefor air moves in via diffusion*

Exhalation - *ribs move in and down, diaphragm releases and moves up, increase in pressure in lung as volume decreases and air moves out via diffusion*

Respiratory system steps

Nasal passageway

Trachea

Bronchi

Bronchioles

Alveoli

Nasal passageway

Moistens and warms air up, mucous and hair to catch foreign particles

Trachea

Lined with cartilage for protection, contains the voice box, lined with cilia and mucous to catch any missed foreign particles

Bronchi

Trachea splits into two bronchi

Bronchioles

Branches split and split again into tiny tubes called bronchioles

Alveoli

Gas exchange

Alveoli cont.

Lining of Alveoli is only 1 cell thick, lined with dense network of capillaries - also 1 cell thick, decreases diffusion distance

O2 transport

Haemoglobin carries O2 around blood - has 4 components

Circulatory system

Double circuit, transports O2 and CO2 around body, LA - left atrium, LV - left ventricle, RA - right atrium, RV - right venticle

Red blood cells

Carries and transport O2 around the body

White blood cells

Fights infections

Plasma

Carries dissolved nutrients e.g. glucose NA+ and CA+

Platelets

Cell fragments involved in blood clotting and healing

Function of digestive system

Breakdown and absorb nutrients

Examples of digestion

**Unabsorbed** and *Absorbed*

**Starch (*****sugars)*** **and Amylase (*****enzyme)*** – simple sugars (glucose)*.*

**Proteins and Protease** – *Amino Acids*.

**Fats and Lipase** – *fatty acids and glycerol*.

Mechanical digestion

Physical breakdown into smaller pieces to increase SA for digestion

Chemical digestion

Use of enzyme to breakdown food into component molecules

Sections of digestive system

Mouth, oesophagus, stomach