CAIE AS LEVEL BIOLOGY - SUMMARIZED NOTES ON THE THEORY SYLLABUS

Flashcards about Cell Structure, Biological Molecules, Enzymes, Cell Membrane and Transport, Chromosomes, Nucleic Acid & Protein Synthesis, Transport in Plants, Transport in Mammals, Gas Exchange, Infectious Diseases, and Immunity.

Magnification

Number of times larger an image is compared to the real size of the object.

Resolution

The ability to distinguish between two separate points; higher resolution means higher detail.

Function of the Cell Surface Membrane

Barrier between cytoplasm and external environment, cell signaling, cell recognition, cell-to-cell adhesion, site for enzyme catalysed reactions, anchoring the cytoskeleton, selection of substances that enter/leave the cell, and formation of Hydrogen bonds with water for stability

Nuclear Pore

Gaps in the nuclear envelope that allow exchange between the nucleus and cytoplasm of mRNA and ribosomes for protein synthesis in addition to protein to help make ribosome, nucleotide, ATP, & some hormones.

Function of Golgi body/complex/apparatus

Collects, processes, modifies and sorts molecules that are ready for transport in Golgi vesicles to other parts of the cell or out of the cell by secretion/exocytosis and also makes lysosomes, glycoproteins and functioning proteins.

Function of Mitochondria

Provides energy for aerobic respiration, synthesizes lipids and is more in areas that require maximal energy.

Role of adenosine triphosphate (ATP)

The energy carrying molecule produced in mitochondria that spreads to parts where needed; energy is released by breaking ATP to ADP, a reversible hydrolysis reaction.

Ribosomes

The site at which mRNA (transcribed from the nucleus) is translated into polypeptides with the help of tRNA, therefore help with protein synthesis.

Lysosomes

A single membrane with no internal structure in animal cells that contains digestive (hydrolytic) enzymes that’s kept separate from rest of cell to prevent damage and is responsible for breakdown of unwanted structures e.g. old organelles or whole cells, in WBC to digest bacteria.

Microtubules

Long hollow tubes that make up the cytoskeleton which helps determine cell shape.

Function of Chloroplasts

Carries out photosynthesis and ATP synthesis.

Function of Cell Wall

Gives the cell its definite shape and prevents it from bursting (by osmosis), allowing turgidity.

Plasmodesmata

Pore-like structures found in cell walls that allow a link between neighbouring cells by fine threads of cytoplasm.

Disaccharide

A sugar molecule consisting of two monosaccharides joined together by a glycosidic bond.

Starch

A macromolecule that is found in plant cells, is made up of amylose and amylopectin, and stores energy.

Glycogen

A macromolecule that is used for the storage of energy is animal cells and is also made from α glucose molecules.

Triglyceride

Forms by the condensation of 3 fatty acid chains and a glycerol molecule, forming an ester bond.

Phospholipid

Hydrophilic head contains a phosphate group and glycerol while the hydrophobic tail contains 2 fatty acid chains.

Primary structure of proteins

The sequence of amino acids in a polypeptide/protein.

Secondary structure of proteins

The structure of a protein molecule resulting from the regular coiling or folding of the chain of amino acids.

Tertiary structure of proteins

The compact structure of a protein molecule resulting from the three-dimensional coiling of the already-folded chain of amino acids.

Quaternary structure of proteins

The three-dimensional arrangement of two or more polypeptides, or of a polypeptide and a non-protein component such as haem, in a protein molecule.

Enzymes

Speed up the rate of a reaction by lowering the activation energy

Activation energy

The energy required in any chemical reaction to break the bonds in reactant molecules so that new bonds are formed to make the product.

Inhibitors

Interfere with enzyme activity and reduce the rate of an enzyme catalysed reaction.

Theoretical maximum rate velocity (Vmax)

The reaction rate is measured at different substrate concentrations while keeping the enzyme concentration constant; as substrate concentration is increased, reaction rate rises until the reaction reaches its maximum rate.

Michaelis–Menten constant (Km)

The substrate concentration that corresponds to half of Vmax; measures the affinity of the enzyme for the substrate.

Fluid mosaic model

Individual phospholipid and protein molecules move around within their own monolayer.

Phospholipid bilayer

Provides the basic structure of membranes; it is selectively permeable and acts as a barrier to most water-soluble substances.

Cholesterol

Regulates the fluidity of a membranes; its hydrophobic region prevents polar molecules from passing through the membrane.

Channel proteins

Water-filled pores that allow charged substances, usually ions, to diffuse through the membrane; have a fixed shape and can be gated to control ion exchange.

Carrier proteins

Can flip between two shapes, and is mainly in active transport where it uses ATP to change shape and carry ions/molecules up the concentration gradient, but can also be involved in passive transport (facilitated diffusion) down the concentration gradient without the use of energy.

Diffusion

The net movement of molecules or ions from a region of high concentration to a region of low concentration.

Facilitated diffusion

Movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient with the help of transport proteins instead of passing through phospholipids.

Osmosis

The diffusion of water molecules from a region of higher water potential (ψ) (less negative) to a region of lower ψ (more negative) through a selectively permeable membrane.

Active transport

Movement of substances from a region of low concentration to a region of high concentration against a concentration gradient using energy from ATP.

Chromosome

The threadlike structure containing DNA and genes.

Chromatin

A combination of DNA wound around histone proteins (basic).

Centromere

The region where chromatids are held together.

The Cell Cycle

Three phases are Interphase, nuclear division, and cell division.

Growth 1 phase

Gap after cell division and before S phase.

S phase

Synthesis of DNA so each chromosome consists of two identical chromatids.

Growth 2 phase

Gap after S phase and before nuclear division (prepares for mitosis).

Nuclear division

Division of nuclei at M phase.

Cytokinesis

Division of cytoplasm between daughter cells, last stage of cell division.

Stem cells

Cells that divide repeatedly by mitosis, and differentiate into specialized cells or remain as stem cells.

Totipotent

Cells that can divide repeatedly to form any other cell in the body.

Pluripotent

Embryotic stem cells that lead to development of the embryo and later the adult; they are not specialized into placenta.

Multipotent

Adult stem cells that are only able to produce a few types of cells e.g. stem cells in bone marrow.

Cancer

Mutation occurs in genes that control cell division, an oncogene, that results in uncontrolled mitosis.

Nucleotides

Basic building block of nucleic acids, such as DNA and RNA; organic compound made up of nitrogenous base, a pentose sugar, and a phosphate group.

Polynucleotide

Many nucleotides are linked together into a long chain forming polynucleotides DNA/RNA.

Gene

A length of DNA which codes for a specific polypeptide or amino acid chain.

Codon

Sequence of three nucleotide bases which code for a specific amino acid.

Transcription

In the nucleus the following happens: DNA unwinds to form two strands (template and non- template) and the template strand acts as a template; free activated RNA nucleotides line up with their complementary base and forms H-bonds; RNA polymerase catalyzes the synthesis of Phosphodiester bonds to form sugar-phosphate backbone; hydrogen bonds between the DNA and mRNA strand are then broken; DNA is reformed; mRNA strand then leaves the nucleus through the nuclear pores.

RNA splicing

Removal of introns from primary transcript.

Xylem vessels

These are dead cells which from a long, narrow and hollow tube to increase capillarity; they transport water unidirectionally (from roots to leaves).

Translocation

Transport of soluble organic substances within a plant.

Transpiration

The process involving the loss of water in the form of water vapour from the aerial parts of the plant.

Arteries

Transport oxygenated blood swiftly to the tissues at high pressures.

Veins

Carry deoxygenated blood back to the heart.

The Circulatory System

The mammalian circulatory system is a closed double circulation where blood passes through the heart twice in one circulation of the body (pulmonary circuit and systemic circuit), contained inside blood vessels.

Tissue fluid

This fluid surrounds all the cells; has almost the same components as plasma, but lacks large plasma proteins which are too large to diffuse through pores in capillaries.

Ventilation of lungs

Replaces alveolar air with air from outside the body to help maintain the diffusion gradient.

Bronchi

Branch to form smaller bronchioles.

Epithelium

These cells make up a tissue that lines the trachea and bronchi and are adapted to remove particles from air before it reaches the lungs.

Ciliated cells

Lined with tiny cytoplasmic extensions known as cilia; responsible for the continual beating of mucus towards the larynx.

Goblet cells

Found in between ciliated cells in large amounts; the upper part of a goblet cell is swollen with mucin droplets that are secreted by the cell; mucous secreted by goblet cells traps pathogens which are then moved out with the help of the cilia.

Mucus

A slimy solution of mucin, which is composed of glycoproteins with many carbohydrate chains that make them sticky and able to trap inhaled particles.

Disease

Ill-health or sickness causes reduced effectiveness of functions, has a set of symptoms, can be poor physical, mental, social well-being.

Antibiotics

Drug that kills or stops the growth of bacteria, without harming the cells of the infected organism.

Immune response

The body’s immune system responding to non-self-antigens by lymphocytes and phagocytes; involves the production of antibodies and the killing of cells that have become infected by pathogens.

Lymphocytes

WBC produced before birth in the bone marrow.

Primary response

There are very few B cells specific to the antigen thus production of antibodies is low.

Secondary response

There are many more antibodies produced as many memory cells divide quickly and differentiate into plasma cells.

Antibodies

Globular glycoproteins with quaternary structure, forming plasma proteins called immunoglobulins.

Specificity of antibodies

Sequence of amino acids in this region make the specific 3-D shape which binds to just one type of antigen; R group interactions with the antigen gives it the specific shape.

Monoclonal antibodies

Highly specific and identical antibodies made by identical B cell clones.

Vaccination

An antigenic material, which could be a live, dead or attenuated micro-organism, or perhaps a harmless form of a toxic (toxoid) or simply surface antigens; allows our immune system to produce the requisite B and T cells without actually suffering the disease, mimicking natural immunity.