CELL: THE UNIT OF LIFE - Unit 3 Biology (Chapter 8)

Flashcards covering key concepts on cell structure, function, and the cell theory from Unit 3 Biology (Chapter 8).

What is Reductionist Biology?

A physico-chemical approach that applies concepts from physics and chemistry to study biology, using analyses of tissues to identify elements and compounds and explain the molecular basis of physiological processes.

Who formulated the cell theory?

Schleiden and Schwann.

Who added the concept that cells arise from pre-existing cells?

Rudolf Virchow (Omnis cellula-e cellula).

What are the two major cell types based on presence of a membrane-bound nucleus?

Prokaryotic cells (no nucleus) and Eukaryotic cells (nucleus present).

Which organelles constitute the endomembrane system?

Endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles.

Ribosomes in prokaryotes and eukaryotes differ in size. What are they?

Prokaryotic ribosomes are 70S (50S + 30S); Eukaryotic ribosomes are 80S (60S + 40S).

What are the main features of mitochondria?

Double-membrane-bound, with cristae and matrix; sites of aerobic respiration; produce ATP; contain circular DNA; divide by fission.

What are plastids and their types?

Pigment-containing organelles: chloroplasts (chlorophyll), chromoplasts (carotenoids), and leucoplasts (starch/oils/proteins).

What is the role of chloroplast structure in photosynthesis?

Chloroplasts have thylakoids arranged in grana, a stroma with enzymes, and chlorophyll; site of photosynthesis; contain their own DNA and ribosomes.

Golgi apparatus function.

Packaging and processing of materials; formation of vesicles; proteins modified in cisternae; cis face receives from ER; trans face ships to destinations; glycoproteins and glycolipids formed there.

Rough vs Smooth Endoplasmic Reticulum.

RER has ribosomes and synthesizes/secretes proteins; SER lacks ribosomes and synthesizes lipids; both are connected to the nuclear envelope.

Lysosomes.

Membrane-bound vesicles with hydrolytic enzymes; digestive processes; acidic pH.

Vacuoles.

Membrane-bound sacs; plant vacuoles large; tonoplast; osmoregulation and storage; some cells have food vacuoles.

Chloroplast structure features.

Double-membrane organelle with inner membrane; thylakoids arranged into grana; stroma contains enzymes; chloroplast DNA; ribosomes; site of photosynthesis.

Ribosomes composition and differences.

70S in prokaryotes (50S + 30S); 80S in eukaryotes (60S + 40S).

Cytoskeleton components and functions.

Microtubules, microfilaments, intermediate filaments; provide mechanical support, shape, motility, and intracellular transport.

Cilia and Flagella 9+2 arrangement.

Axoneme with nine peripheral doublets and two central microtubules; basal body; membrane-covered.

Centrosome and Centrioles.

Centrosome contains two centrioles; basal bodies form cilia/flagella; organize spindle fibers during cell division.

Nucleus features.

Nucleus contains chromatin and nucleolus; nuclear envelope with pores; perinuclear space; usually one nucleus per cell; some cells are multinucleate or anucleate.

Kinetochores.

Disc-shaped structures at centromeres; attach to spindle microtubules during cell division.

Chromosome types by centromere position.

Metacentric, submetacentric, acrocentric, telocentric.

Golgi cisternae orientation.

Golgi cisternae are stacked near the nucleus; cis face receives from ER; trans face delivers to destinations.

Cell membrane structure.

Phospholipid bilayer with cholesterol; proteins (integral and peripheral); glycolipids and glycoproteins; fluid mosaic model.

Membrane transport types.

Passive diffusion and osmosis; facilitated diffusion with carrier proteins; active transport requiring ATP (e.g., Na+/K+-ATPase).

Cell wall components in plants/algae and fungi; PPLO note.

Plant/algal walls: cellulose, hemicellulose, pectins; middle lamella calcium pectate. Fungi: chitin. Mycoplasma and PPLO lack cell walls; Gram staining differences relate to envelope structure.

Gram staining classification.

Gram-positive bacteria: thick peptidoglycan layer; Gram-negative: thinner peptidoglycan with outer membrane; different staining.

Plasmids.

Small circular DNA molecules outside the chromosome; confer antibiotic resistance and other traits; used in genetic transformation.

Prokaryotic cell features.

No membrane-bound nucleus; no membrane-bound organelles; cell wall (usually); 70S ribosomes; circular DNA; may have mesosome and plasmids.

Eukaryotic cell features.

Membrane-bound nucleus and organelles; complex cytoskeleton; extensive endomembrane system; larger cells.

Mitochondria compartments.

Outer membrane, inner membrane with cristae; intermembrane space; matrix; site of oxidative phosphorylation; contain DNA and ribosomes; divide by fission.

Nuclear pores function.

Regulate movement of RNA and proteins between nucleus and cytoplasm.

Endomembrane system vs other organelles.

Endomembrane system includes ER, Golgi, lysosomes, vacuoles; mitochondria and chloroplasts are not part of this system.

Microbodies.

Membrane-bound vesicles containing various enzymes (e.g., peroxisomes) involved in metabolic reactions.

What specific approach does Reductionist Biology utilize?

A physico-chemical approach.

Which two scientific disciplines provide the concepts applied in Reductionist Biology?

Physics and Chemistry.

What Latin phrase did Rudolf Virchow use to express that cells arise from pre-existing cells?

Omnis cellula-e cellula.

Which type of cell lacks a membrane-bound nucleus?

Prokaryotic cells.

What is the sedimentation coefficient for prokaryotic ribosomes?

70S (comprising 50S and 30S subunits).

What are the subunits of a eukaryotic ribosome?

60S and 40S, forming an 80S ribosome.

What internal membrane foldings are characteristic of mitochondria?

Cristae.

What type of plastid is specifically responsible for storing starch?

Amyloplasts (a type of leucoplast).

What are the stacks of thylakoids within chloroplasts called?

Grana.

Which face of the Golgi apparatus is typically oriented towards the Endoplasmic Reticulum?

The cis face.

What is the primary function of the Smooth Endoplasmic Reticulum (SER)?

Synthesizes lipids.

What type of enzymes are found in lysosomes and are responsible for digestive processes?

Hydrolytic enzymes.

What is the membrane surrounding the central vacuole in plant cells called?

Tonoplast.

Is the chloroplast a single or double-membrane organelle?

Double-membrane organelle.

What are the three main components that make up the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments.

What is the specific arrangement of microtubules found in cilia and flagella?

The 9+2 arrangement, with nine peripheral doublets and two central microtubules in the axoneme.

What structure within the centrosome is responsible for organizing spindle fibers during cell division?

Centrioles (specifically, the centrosome as an entirety organizes them).

What are the large openings in the nuclear envelope that regulate molecular transport called?

Nuclear pores.

What specific structure on a chromosome do kinetochores attach to?

Centromeres.

According to the fluid mosaic model, what are the two main types of proteins found in the cell membrane?

Integral and peripheral proteins.

What is an example of active transport mentioned that requires ATP?

\text{Na}^+/\text{K}^+ -ATPase.

What is the primary component of plant cell walls that gives them structural support?

Cellulose.

What class of bacteria is characterized by a thick peptidoglycan layer in its cell wall?

Gram-positive bacteria.

What are small circular DNA molecules found outside the main chromosome in prokaryotes called?

Plasmids.

Do prokaryotic cells possess membrane-bound organelles?

No.

What is the site of oxidative phosphorylation within the mitochondria?

The inner mitochondrial membrane (within the matrix and intermembrane space).

Are mitochondria considered part of the endomembrane system?

No, they are independent organelles.

What is an example of a microbody that contains enzymes to neutralize toxic hydrogen peroxide?

Peroxis