IB HL Biology Topic A - Unity and Diversity (incomplete)

A1.1,1.2

Nucleotide

Phosphate ester of a nucleoside with organic base, pentose sugar, and phosphate.

Cytosine

Pyrimidine base in DNA and RNA, pairs with guanine.

Guanine

Purine base in DNA and RNA, pairs with cytosine.

Adenine

Purine base in ATP, NADP, DNA, and RNA, pairs with thymine.

Thymine

Pyrimidine base in DNA, pairs with adenine.

Pentose

5-carbon monosaccharide sugar.

Condensation

Formation of larger molecules by removing water from smaller components.

Metabolism

when an organism undertakes essential chemical reactions

Reproduction

Produce offspring, sexually or asexually

Sensitivity

Responsive to internal and external stimuli

Homeostasis

Maintain a stable internal environment

Excretion

Produce waste

Nutrition

Exchange materials and gases with the environment

Growth/movement

Move and change shape or size

Cell theory

The cell is the smallest unit of life; cells only arise from pre-existing cells; all living things are made up of cells

Plasma membrane

Outer border maintaining internal chemistry to the exterior (homeostasis)

Genetic material

coded instructions (DNA) that control internal activities within a cell

Ribosomes

Translate the cell's coded instructions into functional elements

Cytosol

Internal fluid serving as a medium for metabolic processes

Sieve tube elements

elements in plants interconnected by plasmodesmata into supracellular assemblies, challenging the idea of independent cells → lacks nucelus

Red blood cells

Lack nucleus and mitochondria when mature, challenging the traditional definition of a eukaryotic cell

Striated muscle fibres

Fusion of muscle cells into long fibers, challenging the idea of discrete cell units

Aseptate Fungal Hyphae

Filamentous structures in fungi for nutrient absorption, challenging the idea of autonomous cells (cells connected without a cell wall between them)

Light microscopy

involves the use of glass lenses to bend light for magnification; can view living specimens in natural colors

Electron microscopy

When images are generated at higher magnification and resolution, but cannot be viewed as living specimens in natural color

Cryogenic electron microscopy

Involves freezing samples to determine molecular structures at near atomic resolution

Magnification

Image size divided by actual size; allows for the calculation of the enlarged image

Prokaryotes

Single-celled organisms with simple cell structure; do not possess membrane-bound organelles; exhibit different shapes

Archaea

prokaryotic; variety of extremophiles and organisms in normal habitats

bacteria

prokaryotic; Large and diverse range of organisms inc. pathogenic forms

Genophore

Single DNA strand in the nucleoid of Archaea

Plasmids

Additional DNA molecules in Archaea, exchanged via bacterial conjugation

Ribosomes (Archaea)

Characteristically small (70S) responsible for protein synthesis in Archaea

Glycocalyx

Slime capsule covering in Archaea

Pili (Archaea)

Hair-like extensions aiding in adhesion or plasmid exchange in Archaea

Flagella (Archaea)

Whip-like projections facilitating movement in Archaea

Eukaryotes

Organisms with cells containing a nucleus and membrane-bound organelles

Endosymbiosis

Evolutionary process where one cell is engulfed by another, leading to assimilation (eukaryotic potential evolution from prokaryotic)

Mitochondria

Organelle responsible for energy production in eukaryotic cells

Cell Wall (Plant)

Made of cellulose, providing structural support in plant cells

Chloroplasts

Organelles responsible for photosynthesis in plant cells

Cytoskeleton

Structural elements in eukaryotic cells, not considered organelles

Light Microscopes

microscopes with low magnification and resolution, view living specimens in natural colors

Electron Microscopes

microscopes which have high magnification and resolution, view dead specimens in monochrome

Prokaryotic Cell Drawing

Genophere as a loop, pili and flagella projecting from the cell wall, 70S ribosomes, appropriate shape

Eukaryotic Cell Drawing (Animals)

Double membraned nucleus, connected ER network, 80S ribosomes, sausage-shaped mitochondria

Eukaryotic Cell Drawing (Plants)

Large central vacuole, cellulose cell wall, double membraned chloroplasts with grana

Abiogenesis

the process of spontaneous emergence of cells from non-living material

Organic Compounds

Complex carbon-based macromolecules found in all cells and organisms

Self-Replication

Capacity for certain organic compounds to reproduce chemical processes in successive cells

RNA

a form of nucleic acid containing the pentose sugar ribose, and the organic bases adenine, guanine, uracil and cytosine.

Protocell Formation

Spontaneous formation of membranes from simple organic molecules

Role of Water

Essential for the formation of life, aids in maintaining stable internal environment

LUCA

Last universal common ancestor, shared source of all extant organisms on Earth

FUCA

first universal common ancestor

Biosignatures

Chemicals produced by cellular processes providing evidence of past or present life

Molecular Clock

Estimates evolutionary divergence timing using mutation rate of biomolecules

Hydrothermal Vents

Heat source interacting with fluid system, likely location of LUCA

Endosymbiosis Evidence

evidence of shared characteristics between organelles and bacteria, suggesting extracellular origins

Multicellularity

Organisms composed of multiple cells operating in unison to support the total lifeform

Emergent Properties

New functions arising from collective actions of individual cells in multicellular organisms

differences between prokaryotic and eukaryotic cells

differences between bacteria and archaea

differences between eukaryotes

Nucleotides

Monomeric units of nucleic acids with sugar, phosphate, and base

nucleic acid

polynucleotide chain of one of two types, deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).

Strand Formation

Process of linking nucleotide monomers via condensation reactions

Base Sequence

Order of nitrogenous bases forming genetic instructions

Pentose Sugar

5-carbon sugar component in nucleotides

Phosphate Group

Component of nucleotides attached to the 5-carbon sugar

Nitrogenous Base

Component of nucleotides attached to the 1'- carbon atom

Condensation Reactions

Chemical reactions involving water linking nucleotide monomers into strands

Phosphodiester Bond

covalent bond between phosphate and 2 sugars (hydroxyl groups)

Polynucleotide Strands

Long strands formed by successive condensation reactions

Complementary Base Pairing

Hydrogen bonding between purine and pyrimidine bases

Chargaff

Scientist who studied nucleic acid composition and base pairing

Purine

Double-ringed bases like guanine and adenine

Pyrimidine

Single-ringed bases like cytosine, thymine, and uracil

Genetic Code

the order of bases in DNA (of a chromosome) that determines the sequence of amino acids in a protein.

Tetranucleotide Hypothesis

Theory suggesting DNA composed of 4 repeating bases

DNA

a form of nucleic acid consisting of two complementary chains of deoxyribonucleotide subunits, and containing the bases adenine, thymine, guanine and cytosine.

Variability in Base Sequence

Essential for DNA to function as genetic material

Chargaff's Data

Evidence disproving the tetranucleotide hypothesis

Chargaff's Experiment

Demonstrated uneven base frequencies, refuting tetranucleotide hypothesis

Purine-to-pyrimidine Bonding

Ensures DNA helix stability by pairing double-ringed purines with single-ringed pyrimidines

DNA vs RNA stability

DNA is stable, RNA is versatile for genetic information transfer

RNA Structure

Single-stranded nucleic acid involved in protein synthesis

DNA Structure

Double-stranded nucleic acid for hereditary information transfer

Directionality of DNA and RNA

Nucleotides form strands with 5' to 3' linkages, DNA is antiparallel

function of nucleic acids

DNA stores genetic instructions via base sequences, RNA aids in protein synthesis

Hershey-Chase Experiment

Proved DNA as genetic material using radioactive labeling of viruses

Nucleosome Structure

DNA wrapped around histone proteins for compacted structure

Organisation of Eukaryotic DNA

DNA complexed with histones forming nucleosomes, condensed into chromatin

nucleotide structure

mRNA

messenger RNA → encodes proteins

tRNA

transfer RNA → carries amino acids

rRNA

ribosomal RNA → forms the ribosome

histones

A type of protein found in chromosomes → bind to DNA, help give chromosomes their shape, and help control the activity of genes

nucleosome

• help to supercoil the DNA, resulting in a greatly compacted structure that allows for more efficient storage

• Supercoiling helps to protect the DNA from damage and also allows chromosomes to be mobile during mitosis and meiosis