Biology

Cell Theory

All living organisms are composed of one or more cells
Cell is the smallest basic unit of life
All cell arise from pre-existing cells

Prokaryotic Cells

Prokaryotic cells lack a true nucleus and membrane-bound organelles, making them smaller and simplier

Eukaryotic Cells

Eukaryotic cells posses a distinct nucleus and various membrane-bound organelles like mitochondria, making them larger and more complex

Cell Membrane

acting as a selective barrier to control substance transport, providing structural support and protection and maintain the stable internal environment of cell

Cell Wall

Provides structural support, mechanical strength, and protection to cells, preventing damage from osmotic pressure and physical stress

Capsule

a well-organized, protective layer of polysaccharide or polypeptide that surrounds the cell wall, acting as a barrier agains desiccation, toxin and immune cells

Ribosomes

Protein synthesis and translation

Plasmid

Provide beneficial traits, such as antibiotic resistance, the ability to degrade toxic substances, or to produce toxins

nucleoid

to house and organize the cell’s genetic material, the circular chromosome

pili

to ensure that the bacterial cells are properly attached to the host surface in which they are living

fragellum

to enable cell motility, allowing bacteria, some archaea, and some eukaryotic cells to move through liquid environments

nucleus

controlling gene expression, orchestrating DNA replication and RNA processing and coordinating protein synthesis and cell division

mitochondria

generate the majority of the cells energy, storing a molecule called ATP, through a process called oxidative phosophorylation

Chloroplast

responsible for photosynthesis, converting light energy into chemical energy and releasing oxygen

Sap vacuole

Maintaining turgor pressure for structural support, storing water, nutrients ions, and waste, and regulating osmotic balance

Golgi apparatus and Secretory resicles

Golgi modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles

Rough and Smooth Endoplasmic Retriculum (RER & SER)

RER has ribosome on its surface for protein synthesis
SER do not has ribosomes, therefore it is responsible for lipid synthesis, detoxification and calcium storage

Cytoskeleton

A system of protein fibres that helps to hold organelles in place and maintain the structure and shape of the cell

Cytoplasm

the cytoplasm surrounds the organelles, it is essential for the cell’s survival as it contains all organelles and many enzymes

Compartmentalization

Compartmentalization is the division of the cytoplasm into membrane-bound organelles, is the defining feature of eukaryotes and provide major advantages

Cell Specialization

After fertilization, the zygote divides to produce unspecialized cells. These cells undergo differentiation, become specialized in structure and function

Stem Cells

Stem cells are unspecialized but have the potential to become specialized

Totipotent

stem cells that can become any cell type and extra-embryonic tissues

Pluripotents

stem cells that can become any cell type but cannot form extra-embryonic tissues

Multipotent

stem cells that can only become limited range of closely related cell types within a specific tissue

Unipotent

Stem cells that can only differentiate into their associated cell types

Lipid Bilayers

the phospholipids form a bilayer that acts as a barrier to certain materials

Membrane Transport

Movement of materials across a membrane will depend on both the size and solubility of the material

Passive Transport

movement from high concentration to low concentration

Active transport

movement from low concentration to high concentration

Simple diffusion

net movement of molecules from a region of higher concentration to low concentration

Facilitation Diffusion

movement of molecules across the cell membrane via the aid of a membrane protein

Osmosis

Diffusion of free water molecules

Hypotonic

low solute level, high free water

Hypertonic

high solute level, low free water

Isotonic

two solutions have equal solute concentration

Water Structures

Water is made up with two hydrogen atoms covalently bonded to an oxygen atom (H2O)

Cohesion

water molecule is able to stick to other water molecules via the formation of hydrogen bonds

Adhesive

attraction to charged or pola surfaces allows water to flow in opposition to gravitational forces

Capillary action

Allow water to be transported up plant stems via a transpiration stream

Solvation

the process by which solvent molecules surround and interact with solute molecules

Metabolic Medium

the capacity of water to dissolve a large variety of substances make it an important medium for metabolic reaction

Transport Medium

Water acts as a vital, polar transport medium in living organisms due to its ability to dissolve substances and flow easily

Buoyancy

the upward force applied to an object in a medium and is determined by the density of the medium
Water has more buoyancy compared with air

Viscosity

a measure of a fluid’s tendency to flow
water is more viscous compare with air

Thermal conductivity

a measure of a medium’s ability to move heat across a temperature gradient
water absorbs and transfer heat more readily than air

Specific Heat Capacity

describes the amount of energy required to raise the temperature of 1g of substance by 1C
water has a high specific heat capacity than air

Carbohydrates

Carbohydrates are made out of carbon, hydrogen, and oxygen, composed of monomers called monosaccharides

Lipid

Lipids are a class of organic molecule composed primarily of hydrocarbon chains or rings

Nucleic Acid

nucleic acid are the genetic material of the cell and composed of recurring monomeric units called nucleotides

Protein

proteins are composed of long chains of recurring monomers called amino acids

DNA replication

DNA is a stable molecule hose sequence is conserved throughout the life of a cell. DNA molecule is replicated when a new cell is required.

DNA Polymerase

DNA polymerase synthesises new strands from the two parental template strand

Polymerase Chain Reaction (PCR)

a method of replicating DNA under laboratory conditions

Gel Eletrophoresis

laboratory technique used to separate and isolate the DNA fragments based on the mass and size

DNA profiling

Technique by which individual’s genome there exists long stretches of DNA made up of repeating elements called short tandem repeats (STRs)

Transcription

the process by which an mRNA sequence is produced from a DNA template

Process of transcription

RNA polymerase binds to the promoter region on the DNA strand, causing the DNA double helix to unwind and separate (initiation). RNA polymerase then moves along the template strand of DNA, reading it in 3’-5’ direction. Free RNA nucleotides pair with the DNA template strand according to CBP and RNA polymerase joins these nucleotides together to form mRNA strand in 5’-3’direction (elongation). When RNA polymerase reaches a terminator sequence on the DNA, transcription stops. The mRNA strand detaches from the DNA template and the two DNA strands re-wind back into a double-helix (termination)

messenger RNA (mRNA)

the transcript copy of the DNA instructions

transfer RNA (tRNA)

carriers the protein subunits (amino acids) to the mRNA transcript

ribosomal RNA (rRNA)

provides the catalytic activity for combining the amino acids according to the mRNA sequence

Translation

Translation involves the synthesis of an amino acid sequence (polypeptide) by the ribosome

process of translation

The small ribosomal subunits binds to the mRNA and scans for the start codon (AUG). The initiator tRNA binds to this codon. The large ribosomal subunit then joins to form the functional initiation complex (initiation). The ribosome moves along the mRNA. tRNA bring amino acids to the ribosome, matching them with the mRNA sequence, creating a growing polypeptide chain (elongation). When a stop codon enters the ribosome, which does not codes for an amino acid, will end the polypeptide. The completed polypeptide chain is released and the ribosomal complex dissembles (termination).

Genetic Code Universal

almost every living organism uses the same code, as the same code codes for the same amino acids in all living things, genetic information is potentially transferrable between species

Genetic Code Degeneracy

As the genetic code has only ~20 amino acids but 64 different codon combinations, more than one codon may code for a single amino acid, allowing the occurence of silent mutations

Mutation

A change in the nucleotide sequence of a session of DNA that encodes for a specific trait

Metabolism

Metabolism describes the totality of all enzyme-catalysed reaction that occur within a living cell or organism

Anabolic Reactions

a metabolic reaction that build up complex molecules fro simplier ones

Catabolic Reactions

a metabolic reactions that break down complex molecules into simplier ones

Enzymes

globular protein which acts as a biological catalyst by speeding up the rate of chemical reaction

Enzyme Specificity

Each enzyme only works with specific substrates. This is because the active site has a unique 3D shape that is complementary to particular substrates. Only substrate with a matching shape can bind to the active stie to form an enzyme-substrate complex.

Adenosine triphosphate (ATP)

a molecule that functions to distribute energy within cells

Cell Respiration

Cell respiration is the controlled release of energy from the breakdown of organic compounds to produce ATP

Anaerobic Respiration

begins with the process of glycolysis, whereby simple sugars (glucose) are partially broken down into two pyruvate molecules with a small yield of ATP

Aerobic Respiration

begins with the process of glycolysis but oxygen is then used to completely break down the pyruvate for a much larger ATP yield

Exergonic Reaction

reaction where energy is being released

Endergonic Reaction

reaction where energy is needed

Photosynthesis

process by which cells synthesis organic compounds (e.g. glucose) from inorganic molecules (CO2 and H2O) in the presence of sunlight

Equation of photosynthesis

6CO2+12H2O=C6H12O6+6O2+6H2O
carbon dioxide + water = glucose + oxygen + water

Cell Respiration vs Gas Exchange

Cell respiration is a chemical process that happens inside cells. It breaks down glucose to produce ATP (energy). Gas exchange is a physical process that happens at respiratory surfaces (e.g. lungs). Oxygen moves into the blood from the air. Carbon dioxide moves out of the blood into the air.