Biology - Properties of Life & Cells

Vocabulary flashcards covering key concepts from the notes on life properties, cell types, and scientific inquiry.

Order

Living organisms are highly organized.

Sensitivity (Response to environment)

Organisms respond to various stimuli.

Reproduction

The ability of organisms to create new life.

Growth & Development

Organisms can grow and develop throughout their life cycle.

Regulation

Mechanisms that help cope with environmental stresses (e.g., cellular interdependence).

Homeostasis

Maintaining internal balance, e.g., sweating to cool off, shivering to heat up.

Energy Processing

Organisms use energy for metabolic activities, e.g., photosynthesis & cellular respiration.

Organization of matter in biology

Atoms → Molecules → Macromolecules → Organelles → Cells → Tissues → Organs & Organ Systems → Organisms/Populations & Communities → Ecosystems → Biosphere.

Features common to all cells

Plasma membrane, Cytoplasm/Cytosol, DNA, Ribosomes.

Prokaryotic cell characteristics

Nucleoid; no membrane-bound organelles; cell wall; some have flagella or pili.

Eukaryotic cell characteristics

Larger than prokaryotes; true nucleus with DNA surrounded by a membrane; membrane-bound organelles.

Hypothesis

A testable and falsifiable statement.

Experimental design

Includes sample size and methods to avoid bias.

Independent variable

Manipulated variable.

Dependent variable

Measured variable.

Results interpretation

Interpreting results by measuring dependent variables and checking for statistical significance.

HEER

Stands for Hypothesis, Experimental design, Experimental variables, Results (interpretation).

Matter

A substance that occupies space and has mass

Elements

Unique forms of matter with specific chemical/physical properties that cannot be broken down by ordinary chemical reactions.

Atom

The smallest unit of matter that retains chemical properties. Made up of protons (+, nucleus), neutrons (neutral, nucleus), and electrons (-, orbitals)

Atomic #

The number of protons in the nucleus.

Isotopes

Different forms of the same atom that vary only in the number of neutrons

Atomic mass

The calculated mean of the mass numbers for the naturally occurring isotopes of an element.

Periodic table organized in which way

By atomic number, into rows and columns based on shared chemical & physical properties.

Bohr model of the atom

A central nucleus (protons + neutrons) with electrons in circular orbitals at specific distances (energy levels).

Octet rule

Atoms are more stable when their outermost (valence) shell is filled with 8 electrons (except the innermost shell, which holds 2).

Electron orbitals

Regions where electrons are most likely to be found, with complex shapes due to wave-like behavior.

Why do atoms form chemical bonds?

Because not all elements have enough electrons to fill their outer shells, they bond to achieve stable electron configurations.

Molecule

Two or more atoms chemically bonded together.

Ions

Atoms that gain or lose electrons to become more stable. Cations = positive (lost electrons), Anions = negative (gained electrons).

# of electrons each electron shell can hold

1st shell (1s): 2, 2nd shell (2s, 2p): 8, 3rd shell (3s, 3p, 3d): 18

Electron transfer

Movement of electrons from one element to another

Ionic bonds

Bonds formed between oppositely charged ions (e.g., NaCl)

Covalent bonds

Bonds where atoms share electrons (single, double, triple bonds). Can be polar (unequal sharing) or non-polar (equal sharing).

Hydrogen bonds

Weak bonds where a hydrogen in a polar covalent bond is attracted to another electronegative atom (important in water & DNA).

What are functional groups?

a group of atoms responsible for the characteristic reactions of a particular compound

OR

Atoms that confer specific properties to hydrocarbons and define chemical behavior

Main functional groups

1. Hydroxyl: Polar, hydrophilic

2. Carboxyl: Acidic, releases H+

3. Amine: Basic, accepts H+

4. Phosphate: Acidic, releases H+

5. Methyl: Nonpolar

6. Carbonyl: Polar, increases polarity

7. Sulfhydryl: Polar, contains sulfur

Proteins

Abundant organic molecules with diverse functions. Polymers of amino acids in a linear sequence

Protein’s monomer

Amino Acids

Structure of an amino acid

Central carbon (α) bonded to an amino group (NH2), carboxyl group (COOH), hydrogen atom, and an R group.

Bond that links amino acids

Peptide bond formed during dehydration reaction.

What determines a protein’s shape and function?

Sequence and number of amino acids

Primary structure of proteins

Unique sequence of amino acids in a polypeptide chain.

Secondary structure of proteins

Folding of polypeptide in some regions (e.g., α-helices, β-sheets)

Tertiary structure of proteins

Overall 3D shape due to hydrophobic, ionic, hydrogen bonding, and disulfide linkages

Quaternary structure of proteins

Formed from interactions of multiple polypeptides (subunits).

Denaturation

Loss of protein’s function due to changes in temperature, pH, or chemicals, without changing primary sequence

Chaperones/Chaperonins

Proteins that assist in proper protein folding and prevent aggregation

Protein Aggregation

Misfolded/unfolded proteins clump into stable aggregates

Protein functions examples

1. Enzymes (amylase, lipase)

2. Transport (hemoglobin)

3. Structural (actin, keratin)

4. Hormones (insulin)

5. Defense (immunoglobulins)

6. Contractile (actin, myosin)

7. Storage (albumin).
   

Lipids

Nonpolar, hydrophobic macromolecules. Function in energy storage, insulation, protection, membranes, hormones.

Fats made of

Fatty acids + glycerol (or sphingosine); also called triglycerides or triacylglycerols

Saturated vs unsaturated fats

• Saturated: no double bonds, solid at room temp.

• Unsaturated: double bonds, bent structure, liquid at room temp.

Omega fatty acids

Essential fatty acids with cis double bonds, e.g., Omega-3.

Waxes

Lipids made of long fatty acid chains esterified to alcohols. Provide waterproofing in nature.

Phospholipids

Lipids with glycerol backbone, 2 fatty acids, and phosphate group. Form bilayers in cell membranes.

Steroids

Lipids with 4 fused carbon rings. Examples: cholesterol, testosterone

Carbohydrate

Energy source and structural macromolecules, made of C:H:O in 1:2:1 ratio.

Carbohydrate monomer

Monosaccharides (simple sugars like glucose, fructose, galactose).

Disaccharides

Two monosaccharides linked by glycosidic bonds (lactose, maltose, sucrose).

Polysaccharides

Long chains of monosaccharides (starch, glycogen, cellulose). Storage and structural roles.

Cellulose

Structural polysaccharide in plants (also used by herbivores like cows).

Nucleic acids

Macromolecules that carry genetic information (DNA, RNA).

Nucleic acid’s monomer

Nucleotides (nitrogenous base + pentose sugar + phosphate group).

DNA

Double-stranded molecule carrying genetic material. Bases pair A-T, G-C. Antiparallel strands.

RNA

Single-stranded molecule involved in protein synthesis. Bases are A, U, G, C

Types of RNA

mRNA (messenger), rRNA (ribosomal), tRNA (transfer), miRNA (micro)

Central dogma of life

DNA → RNA → Protein. DNA transcribed into RNA; RNA translated into protein

Dehydration synthesis

Reaction where monomers bond to form polymers, releasing water

Hydrolysis

Reaction where water breaks polymers into monomers

4 macromolecules & their monomers

1. Proteins → amino acids

2. Lipids → fatty acids + glycerol

3. Carbohydrates → monosaccharides

4. Nucleic acids → nucleotides