Chemistry of Life, Macromolecules, Cell Structure, and Cell Signaling Flashcards

Flashcards covering the chemistry of life, macromolecules, cell structure, membranes, cell signaling, DNA, transcription, and translation.

What are the components of an atom?

A nucleus (protons and neutrons) and electron orbitals.

What are the charges of protons, neutrons, and electrons?

Protons are positive, neutrons are neutral, and electrons are negative.

How are atomic number and mass number defined?

Atomic number is the number of protons; mass number is the sum of protons and neutrons.

What are isotopes?

Atoms of the same element with different numbers of neutrons.

How are radioactive isotopes used?

In dating and medical imaging due to their decay and emission of radiation over time.

Describe covalent bonds.

Strong bonds where electrons are shared (polar or nonpolar).

Describe ionic bonds.

Bonds formed by the transfer of electrons, creating ions (cations/anions).

Describe hydrogen bonds.

Weak attractions between polar molecules, crucial in water and DNA.

What is electronegativity?

The tendency of an atom to attract shared electrons.

List the electronegativity of Oxygen, Nitrogen, Carbon, and Hydrogen in order from strongest to weakest.

Oxygen > Nitrogen > Carbon ≈ Hydrogen

List some properties of water due to hydrogen bonding.

Causes cohesion, adhesion, surface tension, high specific heat, and heat of vaporization.

How does water regulate temperature?

High specific heat and heat of vaporization regulate temperature.

What substances can water dissolve?

Polar and ionic substances.

Define hydrophilic.

Water-attracting (polar/charged).

Define hydrophobic.

Water-repelling (nonpolar molecules like oils).

What is molecular complementarity?

Molecules interact via shape/charge compatibility (e.g., enzyme-substrate).

What are structural formulas?

Show how atoms are bonded and arranged in molecules.

Define monomers and polymers.

Monomers are building blocks; polymers are chains of monomers.

How are monomers linked to form polymers, and how are they broken apart?

Linked by dehydration synthesis (removes water), broken by hydrolysis.

What is the monomer of carbohydrates?

Monosaccharides (e.g., glucose).

What is the polymer of carbohydrates?

Polysaccharides (e.g., starch, cellulose).

What is the linkage in carbohydrates?

Glycosidic bond (covalent bond between sugars).

Prokaryotic vs. Eukaryotic cells.

Prokaryotic: no nucleus, circular DNA, no membrane-bound organelles (bacteria). Eukaryotic: nucleus, linear DNA, membrane-bound organelles.

Are carbohydrates typically hydrophilic or hydrophobic?

Typically hydrophilic (due to hydroxyl groups).

List the types of lipids.

Fats, phospholipids, steroids.

Are lipids true polymers?

No, composed of fatty acids + glycerol.

What is the linkage in lipids?

Ester bond (between glycerol and fatty acids).

Are lipids generally hydrophilic or hydrophobic?

Generally hydrophobic (nonpolar hydrocarbon chains).

What is the monomer of proteins?

Amino acids (20 different types).

What is the polymer of proteins?

Polypeptides.

What is the linkage in proteins?

Peptide bond (between amino group and carboxyl group).

List the structure levels of proteins.

Primary (sequence of amino acids), Secondary (alpha helices, beta sheets), Tertiary (3D folding), Quaternary (multiple polypeptides assembled).

What determines the hydrophilicity of a protein?

R-groups of the amino acids.

What is the monomer of nucleic acids?

Nucleotides (sugar + phosphate + nitrogenous base).

What is the linkage in nucleic acids?

Phosphodiester bond (between phosphate and sugar).

Define the directionality of nucleic acids.

5' to 3' (based on sugar carbon positions).

Are nucleic acids hydrophilic or hydrophobic?

Hydrophilic due to charged phosphate backbone.

Nucleus function

DNA storage, transcription site.

Ribosomes function

Protein synthesis (can be free or bound to ER).

ER function

Rough (protein synthesis), Smooth (lipid synthesis, detox).

Golgi apparatus function

Modifies, packages, ships proteins/lipids.

Mitochondria function

ATP production via cellular respiration.

Lysosomes function

Digestion of waste, damaged organelles.

Cytoskeleton function

Actin (movement), microtubules (structure/transport).

Light microscope vs. electron microscope

Light microscope: live cells, lower resolution. Electron microscope (TEM/SEM): dead cells, high resolution.

Membrane's Phospholipid bilayer properties

amphipathic (hydrophilic heads, hydrophobic tails).

Membrane's fluid mosaic model properties

dynamic movement, embedded proteins.

Membrane's functions

barrier, signaling, transport.

Passive transport

diffusion (small nonpolar), osmosis (water), facilitated (via proteins).

Active transport

uses ATP, goes against gradient.

Bulk transport

Endocytosis (in), Exocytosis (out).

Concentration gradient

difference in solute concentration.

Electrochemical gradient

ion concentration + charge difference across membrane.

Ligands definition

molecules that bind receptors (hydrophilic/hydrophobic).

Receptors of Cell Signaling

Ion channel-linked, G-protein-coupled receptors (GPCR), Enzyme-linked (e.g., tyrosine kinase).

Signal transduction definition

receptor → intracellular proteins → response.

Second messengers definition

cAMP, Ca2+, IP3 amplify signal.

Phosphorylation cascades definition

common activation method.

Cell Signaling type Autocrine definition

self

Cell Signaling type Paracrine definition

local

Cell Signaling type Endocrine definition

hormone

Cell Signaling type Juxtacrine definition

contact

DNA Structure

Double helix: two strands, antiparallel.Base pairs: A-T (2 H-bonds), G-C (3 H-bonds).Backbone: sugar-phosphate (phosphodiester bonds).

DNA complementray base pairing enables

replication and transcription.

DNA 5' end

phosphate

DNA 3' end

hydroxyl

DNA Replication

Semi-conservative

DNA replication enzyme Helicase

unwinds DNA.

DNA replication enzyme Primase

RNA primer.

DNA replication enzyme DNA polymerase III

adds nucleotides (5' to 3').

DNA replication enzyme DNA polymerase I

replaces RNA primers.

DNA replication enzyme Ligase

seals Okazaki fragments.

Transcription

Template strand is read 3' to 5'; RNA built 5' to 3'.

Transcription enzymes

RNA polymerase.

Transcription steps definition

initiation (promoter), elongation, termination (terminator sequence).

Eukaryotic RNA Processing steps

5' cap, Poly-A tail, splicing (removal of introns).

Transcription

mRNA carries the message to cytoplasm.

Translation definition

Ribosome reads mRNA 5' to 3'.

Translation steps

Initiation: start codon (AUG), small/large ribosome subunits assemble. Elongation: amino acids added, peptide bonds formed. Termination: stop codon (UAA, UAG, UGA), release factor binds.

Correct sequence determined by

start from AUG to determine correct sequence.

Transcription Product

polypeptide → folds into functional protein.