Cell Biology Flashcards
What are the major differences between prokaryotic and eukaryotic cells?
Prokaryotic Cells: No nucleus, circular DNA, no membrane-bound organelles, smaller size (~1-10 µm)
Eukaryotic Cells: Nucleus, linear DNA, membrane-bound organelles, larger size (~10-100 µm)
What structures are unique to prokaryotic cells?
Cell wall with peptidoglycan, flagella for movement, and plasmids (extra-chromosomal DNA)
What organelles are present in all eukaryotic cells?
Nucleus, endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, peroxisomes, and cytoskeleton
What is the function of the cell membrane?
The cell membrane provides structural support, regulates the passage of substances, facilitates communication, and houses receptors
What is the structure of the cell membrane?
A phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates (forming the glycocalyx)
What are the main components of the cytoplasm?
Cytosol (intracellular fluid), organelles, and cytoplasmic inclusions (e.g., glycogen, lipids, pigments).
What is the primary function of the nucleus?
Stores genetic material (DNA) and regulates gene expression and cell division
What are the components of the nucleus?
Nuclear envelope, nucleoplasm, nucleolus, and chromatin (euchromatin and heterochromatin)
What is the role of the nucleolus?
Synthesizes ribosomal RNA (rRNA) and assembles ribosome subunits
What is the function of mitochondria?
Produces ATP through oxidative phosphorylation; also involved in apoptosis
What is the difference between rough and smooth endoplasmic reticulum?
Rough ER: Has ribosomes, synthesizes proteins for secretion and membrane insertion
Smooth ER: Synthesizes lipids, metabolizes carbohydrates, and detoxifies drugs
What does the Golgi apparatus do?
Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles
What are lysosomes, and what is their function?
Membrane-bound vesicles containing enzymes for digestion of macromolecules and cellular debris
What is the function of peroxisomes?
Break down fatty acids and detoxify harmful substances, producing hydrogen peroxide
What are ribosomes composed of, and what is their function?
Composed of rRNA and proteins, they synthesize proteins based on mRNA instructions
What are the main components of the cytoskeleton?
Microtubules, actin filament and intermediate filaments
What are the functions of microtubules
Maintain cell shape, transport organelles, and form the mitotic spindle during cell division
How do actin filaments contribute to cell motility?
Facilitate cytoplasmic streaming, endocytosis, and cell locomotion (e.g. in pseudopodia)
What are the main types of membrane transport?
Passive Transport - Diffusion, osmosis, and facilitated diffusion
Active transport - Requires energy (e.g. Na+/K+ pump)
Endocytosis - Phagocytosis, pinocytosis, receptor-mediated endocytosis
Exocytosis - Vesicular transport out of the cell
What is the difference between phagocytosis and pinocytosis?
Phagocytosis: Engulfing large particles (e.g. bacteria)
Pinocytosis: Engulfing fluids and dissolved solutes
What are the types of cell signalling?
Autocrine: Signals act on the same cell
Paracrine: Signals affect nearby cells
Endocrine: Hormones travel through the bloodstream
Direct: Gap junctions facilitate ion and molecule transfer
What are the main types of cell membrane receptors?
G-protein-coupled receptors
Ion channel-linked receptors
Enzyme-linked receptors (e.g. receptor tyrosine kinases)
Intracellular receptors for lipid-soluble signals
What is the central dogma for molecular biology?
DNA –> RNA –> Protein
Where does translation occur and what is required?
Occurs in the cytoplasm on ribosomes, requiring mRNA, tRNA and amino acids
What are the phases of the cell cycle?
G1: Cell growth
S: DNA replication
G2: Preparation for mitosis
M: Mitosis (division of nucleus) and cytokinesis
What is the significance of checkpoints in the cell cycle?
Ensure proper cell division and prevent errors like DNA damage
What are the two types of programmed cell death?
Apoptosis: Controlled, energy-dependent process for removing damaged or unnecessary cells
Necrosis: Uncontrolled cell death due to injury, leading to inflammation
