Cells and the Molecules of Life

Flashcards covering key vocabulary related to cells, the molecules of life, cell structures, and cellular processes from the lecture notes.

Proteins

The most abundant macromolecules in cells, consisting of chains of 20 different amino acids whose sequence determines their 3D structure.

Nucleic acids

Macromolecules that serve as carriers of genetic information (e.g., DNA and RNA).

Phospholipids

Amphipathic molecules with a hydrophilic ('water-loving') head and a hydrophobic ('water-fearing') tail, forming lipid bilayers in membranes.

Saccharides

Also known as sugars or carbohydrates, one of the macromolecules of life.

Prokaryotic cells

Fundamental units of life that lack a nucleus and other membrane-bound organelles, typically smaller than eukaryotic cells.

Eukaryotic cells

Fundamental units of life that possess a nucleus and other membrane-bound organelles, can vary greatly in shape and size.

Model organisms

Simple organisms (e.g., E.coli, yeast, mouse) used to learn about molecular biology due to shared fundamental cellular features.

Phylogenetic tree

A diagram that depicts the evolutionary relationships between living organisms, all descended from a common ancestral cell.

Enzymes

Proteins that act as catalysts for specific chemical reactions in cells.

Structural proteins

Proteins that provide stability and support, such as the filaments of the cytoskeleton, which regulate cell shape and intracellular transport.

DNA (deoxyribonucleic acid)

A nucleic acid consisting of four different nucleotides (A, G, T, C) that forms a double helix, with complementary strands (A binds to T, C binds to G).

Complementarity (DNA)

The principle where Adenine (A) always binds to Thymine (T) and Cytosine (C) always binds to Guanine (G), which is essential for DNA copying and heredity.

Heredity

The process by which genetic information (DNA) is copied and passed from one generation to the next.

Genes

Functional units of a DNA strand that encode information for proteins or non-coding RNAs.

RNA (ribonucleic acid)

A nucleic acid transcribed from DNA; messenger RNAs (mRNAs) are translated into proteins, while non-coding RNAs are not.

Amphipathic molecules

Molecules, like phospholipids, that have both hydrophilic ('water-loving') and hydrophobic ('water-fearing') properties.

Cellular membranes (biomembranes)

Bilayered phospholipid structures that surround cells and organelles, separating internal aqueous liquids from the environment and creating compartments.

Compartments (eukaryotic cells)

Specialized regions within eukaryotic cells, often surrounded by a membrane, that perform different functions.

Organelles

Membrane-surrounded, functionally specialized compartments within eukaryotic cells (e.g., nucleus, ER, Golgi, mitochondria, chloroplasts, lysosomes).

Cytoplasm

The entire content of a eukaryotic cell, excluding the nucleus.

Cytosol

The aqueous part of the cytoplasm, excluding organelles.

Nucleus

A defining organelle of eukaryotic cells, enclosed by the nuclear envelope, containing the cell's genetic material (chromatin/chromosomes).

Chromatin

DNA wrapped around proteins called histones, forming the genetic material within the nucleus.

Histones

Proteins around which DNA is wrapped to form chromatin in eukaryotic cells.

Chromosomes

Linear pieces of chromatin organized within the nucleus of eukaryotic cells.

Nuclear envelope

A double membrane (inner and outer) that encloses the nucleus.

Nuclear pores

Channels in the nuclear envelope that regulate the exchange of molecules between the nucleus and the cytoplasm.

Endoplasmic Reticulum (ER)

A network of membrane-enclosed sacs (cisternae) connected to the nuclear envelope, involved in lipid biosynthesis (smooth ER) and protein synthesis/modification (rough ER).

Cisternae

Membrane-enclosed sacs that constitute parts of the endoplasmic reticulum and the Golgi apparatus.

Smooth ER

Section of the ER that is the primary site of lipid biosynthesis.

Rough ER

Section of the ER characterized by ribosomes on its surface, involved in translating mRNAs into proteins and producing membranes and transport vesicles.

Ribosomes

Large molecular complexes of RNA and protein subunits responsible for translating messenger RNAs (mRNAs) into proteins; found on the rough ER and free in the cytosol.

Golgi Apparatus

A system of membrane-bounded sacs (cisternae) that receives and modifies proteins and lipids from the ER, then sorts and packages them into transport vesicles.

Cis face (Golgi)

The 'receiving' side of the Golgi apparatus, where transport vesicles typically arrive from the ER.

Trans face (Golgi)

The 'shipping' side of the Golgi apparatus, where modified proteins and lipids are released in transport vesicles.

Lysosomes

Digestive organelles containing enzymes that degrade macromolecules, functioning optimally in acidic conditions.

Mitochondria

Organelles with two membranes (inner membrane folded into cristae) that convert the chemical energy of nutrients into ATP through cellular respiration, consuming oxygen.

ATP

Adenosine triphosphate, the primary energy currency used for many cellular processes.

Cellular respiration

The process carried out in mitochondria that consumes oxygen to convert the chemical energy from nutrients into ATP.

Cristae

The folds of the inner mitochondrial membrane, increasing the surface area for cellular respiration.

Chloroplasts

Organelles found in plants and algae, containing chlorophyll within an internal thylakoid system, responsible for photosynthesis.

Chlorophyll

A pigment within chloroplasts that helps capture light energy for photosynthesis.

Photosynthesis

The process performed by chloroplasts in plants and algae, converting carbon dioxide and water into sugars and oxygen using light energy.

Thylakoids

An internal membrane system within chloroplasts that contains chlorophyll.

Cytoskeleton

A network of long protein filaments (microtubules, actin filaments, intermediate filaments) extending throughout the cytoplasm, providing stability, organizing the cell, and facilitating transport.

Microtubules

Dynamic filaments of the cytoskeleton made of tubulin subunits, involved in cell organization and transport.

Actin filaments

Dynamic filaments of the cytoskeleton made of actin subunits, involved in cell organization and transport.

Intermediate filaments

Stable filaments of the cytoskeleton that provide structural support.

Tissues

Groups of cells organized in animals and plants that are physically connected and communicate with each other.

Tight junctions

Cell junctions that prevent fluid leakage between cells and restrict protein movement within the cell membrane.

Anchoring junctions

Cell junctions that bridge the cytoskeleton of neighboring cells, providing strong adhesion.

Gap junctions

Small channels between neighboring cells that allow for the exchange of small molecules and electric current.

Cell cycle

A very similar program that all eukaryotic cells use to divide, consisting of G1, S, G2, and M phases.

Replication (DNA)

The essential process during the S phase of the cell cycle where the hereditary information (DNA) is copied.

G1 phase

The first gap phase of the cell cycle where cells perform their specific functions.

S phase

The synthesis phase of the cell cycle during which the cell replicates its DNA.

G2 phase

The second gap phase of the cell cycle where the cell prepares for cell division, typically shorter than G1.

M phase

The mitotic phase of the cell cycle where cell division (mitosis) occurs.

G0 phase

A resting phase entered by cells that stop dividing, usually from the G1 phase.

Archaea

A domain of prokaryotic organisms that are evolutionarily more closely related to Eukaryota than Bacteria, often living in extreme environments.

Nucleoid (prokaryotic)

The region in prokaryotic cells where the main circular DNA molecule (genome) is located, as prokaryotes lack a nucleus.

Plasmids

Additional small, circular DNA molecules found in prokaryotic cells, separate from the main genome.