IB biology HL terms

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unicellular organism

An organism made up of one cell.

Multicellular organism

Organism made up of many cells

metabolism

All of the chemical reactions that occur within an organism

emergent properties

Characteristics of the whole organism including the fact that we are alive
Arise from the interaction of the component parts of a complex structure
- The whole is greater than the sum of its parts

therapeutic stem cells

Stem cells that are used as therapies for certain diseases.

binary fission

The chromosome is replicated semi-conservatively, beginning at the point of origin
Beginning with the point of origin, the two copies of DNA move to opposite ends of the cell
The cell elongates (grows longer).
The plasma membrane grows inward and pinches off to form two separate, genetically identical cells

Compartmentalization

the formation of compartments within the cell by membrane-bound organelles

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

80S ribosomes

larger ribosomes found in eukaryotes

70s ribosomes

smaller ribosomes found in prokaryotes

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

mitochondria

An organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur.

lysosome

cell organelle filled with enzymes needed to break down certain materials in the cell

microtubules

A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.

centrioles

a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

vesicle

A membrane bound sac that contains materials involved in transport of the cell.

vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

nucleolus

Found inside the nucleus and produces ribosomes

RER

An endomembrane system covered with ribosomes where many proteins for transport are assembled.

SER

An endomembrane system where lipids are synthesized, calcium levels are regulated, and toxic substances are broken down.

chromatid

one half of a duplicated chromosome

Triglycerides

an energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid.
Formed with condensation
Ester bond
- Bond formed between each fatty acid and the glycerol
Used as energy stores
Energy from them can be released by aerobic cell respiration
Don't conduct heat well → used as heat insulators

Phospholipid

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

bilayer

a layer that is two molecules thick

amphipathic molecule

A molecule that has both a hydrophilic region and a hydrophobic region.

hydrophobic

Having an aversion to water
non-polar
do not dissolve in water

hydrophilic

Having an affinity for water
polar molecules
dissolve in water

integral proteins

penetrate the hydrophobic interior of the lipid bilayer
Are amphipathic
Embedded in the membrane

peripheral proteins

bound to the surface of the membrane
Are polar(hydrophilic)
Attached to the outside of the membrane

channel protein

A membrane protein, specifically a transport protein, that has a hydrophilic channel that certain molecules or atomic ions use as a tunnel.
Allow passive transport(no energy needed) between the inside and outside of the membrane

carrier protein

Bind to substances on the outside of the membrane
Change shape to transport the substance across the membrane

protein pump

Carrier protein that change their shape using energy

recognition protein

Help the cell differentiate between self and non-self cells

receptor protein

Usually span the whole membrane
Relay info between the inside and outside

enzymes

Enhance the rate of reaction that happens at membrane level
Globular proteins that work as catalysts
- Speed up chemical reactions without being altered themselves
Often called biological catalysts

endocytosis

When the cell engulfs materials from outside the cell

phagocytosis

absorption of solids

Pinocytosis

absorption of liquids

exocytosis

The process of ejecting material from the cell

diffusion

facilitated or simple
The movement of particles from a region of high concentration to a region of low concentration
The result of random motion of particles

osmosis

The passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration across a partially permeable membrane

prophase

DNA supercoils causing the chromatin to condense.
Nucleolus disappears.
Nuclear membrane disintegrates.
Spindle fibres (made of microtubules) start to form (and are completely formed by the end of prophase).
Centrioles (absent from plant cells) move to opposite poles.

metaphase

Spindle fibres bind to the centromere of sister chromatids and cause their movement towards the equatorial plate.
Sister chromatids are aligned at the equatorial plate at the end of metaphase.

anaphase

shortest phase
Sister chromatids are separated (now known as chromosomes) and pulled to opposite poles by the spindle fibres

telophase

The chromosomes have reached the poles.
A nuclear membrane starts to reform at each pole.
A nucleolus appears in each new nucleus.
The spindle fibres disintegrate.
The cell elongates in preparation for cytokinesis.
In some cases, the invagination of the membrane is also visible (marking the beginning of cytokinesis).

interphase

The most active and longest part of the cell cycle
3 important phases: G1, Synthesis, G2

G1

occurs in the cytoplasm
The cell grows and functions normally undergoing everyday processes.
Rapid protein synthesis takes place allowing the cell to grow in size.
Proteins required for DNA synthesis (the next phase) are made.
Mitochondria and chloroplasts (in the case of plant cells) are replicated. This also continues in S phase.

S

occurs in the nucleus
The amount of DNA doubles as DNA replication takes place.
The genetic material is duplicated but no chromosomes are formed yet.

G2

occurs in the cytoplasm
Protein synthesis occurs to produce the proteins needed for cell division, such as microtubule proteins that will make up a mitotic spindle. The cell is actively preparing for cell division.

Cyclins

A family of proteins that control the progressions of cells through the cell cycle
Cells cannot progress to a new stage if the specific ______ doesnt reach a certain concentration
Bind to enzymes CDKs(______-dependent kinases) and activate them
Activated CDKs and attach phosphate groups to other proteins in the cell
Attachment to proteins triggers them to be active and carry out tasks

simple diffusion

Diffusion that doesn't involve a direct input of energy or assistance by carrier proteins.

facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

nucleic acids

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus
Comprise DNA and RNA
Chemicals used to make genes
Chains of subunits called nucleotides

proteins

Astonishingly varied in structure
Carry out many different tasks
- Controlling chemical reactions in cells by acting like enzymes
Composed of one or more chains of amino acids
Amino acids
- Contain carbon, hydrogen, oxygen and nitrogen
- 2 of the 20 amino acids contain sulfur as well

cerbohydrates

Characterized by composition
Composed of carbon, hydrogen and oxygen
- Hydrogen and oxygen ratio: 2:1

lipids

Broad class of non-polar molecules
- Include waxes, steroids, fatty acids, triglycerides
Solid or oils(if liquid) at room temperature

nucleotides

Contain carbon, hydrogen, oxygen, nitrogen and phosphorus
2 types → ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)

anabolism

Reaction that build up larger molecules from slayer ones

catabolism

Where larger molecules are broken down into smaller ones

cohesion

Attraction between molecules of the same substance

adhesion

An attraction between molecules of different substances

Monosaccharides

glucose, fructose, galactose
single sugar units
combine through condensation

Disaccharides

sucrose, lactose, maltose
2 monosaccharides linked together

Polysaccharides

Carbohydrates that are made up of more than two monosaccharides

condensation

involves the combination of subunits and yields water

Fatty acids

chains of carbon atoms bonded to hydrogen atoms
either saturated or unsaturated

saturated fatty acids

Only single bonds
As many hydrogens as possible

unsaturated fatty acids

Presence of one or more double bonds
- Mono → one
- Poly → many
Not max amount of hydrogens

cis unsaturated

Hydrogen atoms on the same side
Bend in the hydrocarbon chain
Not good at packing together in regular arrays like saturated acids
- Lowers melting point
Triglycerides with these are usually liquid at room temperature

trans unsaturated

Hydrogen atoms on opposite sides
Do not bend
Have a higher melting point
Produced artificially by partial hydrogenation of vegetable or fish oils
- Done to produce solid fats like in margarine

peptide bond

The chemical bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid

oligopeptides

chains of fewer than 20 amino acids

open reading frame

The base sequence that codes for a polypeptide

fibrous proteins

Are elongated
Usually with repeating structure

globular proteins

Intricate shape - globular
Often includes parts that are helical or sheet-like
Polypeptides gradually fold up as they are made → the conformation is stabilised by bonds between the R groups

proteome

the entire set of proteins expressed by a given cell or group of cells

substrate

Substances that enzymes convert into products

active site

Region on the enzyme to which the substrate binds
Shape and chemical properties of the active site and substrate match
- Allows substrate to bind but not other substances
Substrates are converted to products when they are bound then freed

enzyme activity

The catalysis of a reaction by an enzyme

collision

the coming together of a substrate molecule and an active site
Occurs due to random movement
Occurs at correct alignment

denaturation

In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix.

complementary base pairing

A is always with T(U in RNA)
G is always with C
Rule that one base always pairs with another

anaerobic respiration (glycolysis)

Respiration that does not require oxygen
glucose --> lactate or ethanol + carbon dioxide
ADP ↷ ATP
glucose --> 2 pyruvate + (2 ATP are produced)
2 pyruvate --> fermentation --> lactate or ethanol + carbon dioxide
2 pyruvate + oxygen --> aerobic respiration

aerobic respiration

glucose+oxygen --> carbon dioxide+water
ADP ↷ ATP

Chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

pigment

Light-absorbing molecule

photolysis reaction

H2O --> 4e-+4H-+O2
"light disintegration"

photolysis

the breaking of water molecules by the piss baby chlorophyll

endothermic

Chemical reaction that involves putting in energy
Reaction with oxygen as a product are usually endothermic in living systems
Reaction combining small molecules to make a larger one are also usually endothermic (carbohydrate is much larger than CO2 and H2O

Activation energy (Ea)

Ea
Minimum energy needed to start a reaction
Measured from reactants to peak of the curve
Energy released in the reaction is ΔH → from products right to reactant level
At peak reactants either follow through with reaction or they fall back
- Collision theory(correct geometry, enough energy and collision need to happen)

transition state (TS)

peak of curve
where reactants have the potential to go into products

Inhibitors

used to slow down a chemical reaction

competitive inhibitors

Interfere with the active site
When they are there the substrate cannot bind
Compete with substrate for active site

non-competitive inhibitors

Bind to a location other than the active site
Change the shape of the enzyme so substrate can't bind

alloristic interaction

Substances that regulate enzymes by binding to special sites

alloristic site

The site to which substances bind to on the enzyme to regulate it