unit 1: cellular biology

What are the fundamental building blocks of all living organisms?

Cells

What is the smallest type of organism?

Unicellular organisms

What is the largest type of organism?

Multicellular organisms

What do all cells share in common?

Membranes, DNA as genetic material, and cytoplasm

What is the role of membranes in cells?

To control entry and exit from the cell

What is the primary component of cytoplasm?

Water

What drives cell activities?

Chemical reactions catalyzed by enzymes

What is the cell theory?

1. All living organisms are composed of cells. 2. Cells are the smallest unit of life. 3. Cells arise from pre-existing cells.

Why are viruses not considered living?

They do not meet the criteria of the cell theory.

What is a hypothesis?

A specific, testable prediction about what is expected to happen in an experiment.

What is a theory in scientific terms?

A well-established principle developed to explain aspects of the natural world, based on repeated observation and testing.

What are the two types of metabolic reactions?

Anabolic (build larger molecules) and catabolic (break down larger molecules).

What is the function of autotrophs?

To synthesize carbon compounds from smaller substances using external energy sources.

What is the difference between sexual and asexual reproduction?

Sexual reproduction involves two parents and genetic variation, while asexual reproduction involves one parent and produces identical offspring.

What is excretion?

The process of eliminating metabolic waste from an organism.

What is the significance of surface area to volume ratio in cells?

A larger ratio allows for more efficient exchange of materials in and out of the cell.

What are emergent properties?

Complex functions that arise from the interaction of specialized cells.

What is the role of microscopes in biology?

To magnify cells and biological specimens for examination.

How is the size of microscopic objects measured?

Using a graticule scale calibrated with a stage micrometer.

What are qualitative observations?

Descriptive observations recorded in notes, drawings, or photographs.

What are quantitative observations?

Measurements that provide numerical values, such as length or time.

What is the process of binary fission? +

A method of asexual reproduction in prokaryotes where genetic material is copied and split. +

What is the role of enzymes in cellular activities?

To catalyze chemical reactions within the cell.

What is homeostasis?

The maintenance of stable internal conditions despite external changes.

What is the function of chloroplasts in unicellular organisms like chlorella?

To perform photosynthesis.

What is the significance of cell differentiation in multicellular organisms?

It allows cells to specialize for specific functions, contributing to complex organismal tasks.

What is the primary method of reproduction in eukaryotes?

Mitosis, meiosis, or fission.

What is hematoxylin used for?

A basic dye with purplish blue color that stains structures with DNA and RNA, such as the nucleus and endoplasmic reticulum.

What does eosin stain?

An acidic dye that stains acidic structures such as cytoplasm and cell walls, giving them a reddish or pink color.

What is the purpose of Masson's Trichrome stain?

It is used to differentiate smooth muscle and collagen fibers.

What does the Ziehl Neelsen stain identify?

It is used to identify acid-fast bacillus (tuberculosis) in lung tissue.

Why are fluorescent stains used?

To identify proteins of interest in a cell, as traditional dyes lack specificity at the molecular level.

How do fluorescent microscopes work?

They use two sets of filters to allow only specific wavelengths of light to pass, exciting the fluorescent dye and detecting emitted light.

What is immunofluorescent microscopy?

A technique where fluorescent dyes are coupled with antibodies to stain specific molecules in cells or the extracellular matrix.

What is the resolution limit of light microscopes?

Light microscopes can only resolve objects greater than 0.2µm apart.

What is the advantage of electron microscopy?

It uses an electron beam to achieve a limit of resolution of about 5nm, allowing for detailed imaging of cell ultrastructure.

What is scanning electron microscopy (SEM) used for?

It is used for detailed study of the surface of a specimen.

What does transmission electron microscopy (TEM) study?

It is used to study the internal ultrastructure of cells by passing an electron beam through a thin section of the specimen.

What is freeze fracture technique?

A method where a specimen is rapidly frozen and fractured to expose structures within the cell.

What are prokaryotes?

Single-celled organisms that lack a membrane-bound nucleus and organelles, typically between 1 to 2 micrometers in length.

What is the key feature of prokaryotic cells?

They have a cell wall composed of peptidoglycan, which maintains cell shape and provides protection.

What is the difference between gram-positive and gram-negative bacteria?

Gram-positive bacteria have simpler cell walls with large amounts of peptidoglycan, while gram-negative bacteria have less peptidoglycan and an additional outer membrane.

What is binary fission?

A method of asexual reproduction in which a parent cell divides into two genetically identical daughter cells.

What is conjugation in bacteria?

The transfer of DNA between two bacterial cells that are temporarily joined.

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have a nucleus and membrane-bound organelles, while prokaryotic cells do not.

What is the function of the cell membrane?

It controls the entry and exit of substances through active transport and facilitates cell communication.

What is the role of ribosomes in eukaryotic cells?

Ribosomes carry out protein synthesis and are composed of RNA and protein.

What is the function of the Golgi apparatus?

It collects, packages, modifies, and distributes materials for secretion or delivery to other organelles.

What are lysosomes?

Intracellular digestive centers that contain enzymes for breaking down various biomolecules.

What is the function of mitochondria?

They produce ATP and have their own circular DNA, surrounded by a double membrane.

What is the role of chloroplasts?

They are involved in photosynthesis and contain pigments necessary for the process.

What are vacuoles used for in plant cells?

They are used for storage and help maintain turgor pressure against the cell wall.

What is the cytoskeleton?

A network of protein filaments in the cytosol that provides shape and facilitates movement in the cell.

What are cilia and flagella?

Cilia are short, hair-like structures that move fluid over the cell surface, while flagella are longer and propel the cell in a specific direction.

What is the difference between animal and plant cells regarding cell walls?

Animal cells do not have cell walls, while plant cells have cell walls made of cellulose.

What is the significance of phospholipids in cell membranes?

They form a bilayer that acts as a barrier, with hydrophobic tails facing inward and hydrophilic heads facing outward.

What is facilitated diffusion?

A process that involves carrier and channel proteins to help substances move across the membrane along their concentration gradient.

What is osmosis?

The passive movement of water across a partially permeable membrane from a hypotonic to a hypertonic solution.

What are aquaporins?

Protein channels that facilitate the movement of water molecules across cell membranes.

What is the role of membrane proteins?

They assist in transport, communication, and maintaining the structure of the cell membrane.

What is the function of the endoplasmic reticulum?

It is involved in the transport of materials within the cell, with smooth ER focusing on lipid transport and rough ER on protein transport.

What are plastids?

Double membrane organelles responsible for manufacturing food and storing it, such as amyloplasts for starch storage.

What type of molecules do active transport proteins carry?

Water-soluble molecules that are ion specific.

What determines membrane permeability?

Size and charge of the substances.

Which substances move easily across a membrane?

Small, non-polar substances.

What are glycolipids?

Phospholipids with carbohydrate chains attached, found on the extracellular part of the membrane.

What role do glycoproteins play in the cell membrane?

They are proteins with carbohydrate chains attached, important for cell adhesion and identification.

What is the function of cholesterol in the cell membrane?

To determine membrane fluidity and allow effective function at a wider range of temperatures.

How do unsaturated fatty acids affect membrane fluidity?

They have double bonds that prevent tight packing, resulting in lower melting points.

What is endocytosis?

The process that allows macromolecules to enter the cell by enclosing them in a vesicle.

What is exocytosis?

The process that allows substances to exit the cell, essentially the opposite of endocytosis.

What are gated ion channels?

Specialized channels that allow ions to pass through membranes and can be opened or closed by stimuli.

What triggers neurotransmitter-gated channels?

Binding of neurotransmitters like acetylcholine, allowing positive ions to pass through.

What is the sodium-potassium pump?

A pump that uses ATP to move sodium and potassium ions against their concentration gradients.

What is coupled transport?

The process where the movement of one molecule down its gradient drives the transport of another molecule against its gradient.

What is the role of cell-adhesion molecules (CAM)?

To facilitate connections between cells, which can be stable or temporary.

What are desmosomes?

Structures that help form flexible sheets of cells in organs, holding cells together during stretching.

What are plasmodesmata?

Tubes in plant cells that connect the cytoplasm of adjacent cells, allowing material exchange.

What is solvation?

The combination of a solvent with molecules or ions of a solute.

How does water's polarity affect its role as a solvent?

Water's partial charges attract polar solutes, allowing them to dissolve.

What is the significance of water's partial negative and positive charges?

They allow water to interact with and dissolve polar solutes.

What attracts positively charged ions in water?

The partial negative oxygen pole of water.

What attracts negatively charged ions in water?

The partial positive hydrogen pole of water.

What are the three steps to solvation?

1. Particles of solute separate from each other. 2. Water particles separate from each other. 3. Separated solute and water particles combine to make a solution.

What happens to a cell in a hypertonic solution?

Water moves out of the cell, causing it to shrink (crenation).

What is the function of a contractile vacuole?

It collects excess water from the interior of the cell and empties it to prevent swelling and bursting.

What occurs when cells are placed in a hypotonic solution?

Water moves into the cell, causing it to swell.

What is turgor pressure?

The pressure a fluid exerts in a confined space, important for plant cell structure.

What is supercoiling of DNA?

The coiling of DNA molecules to make chromosomes shorter and wider during mitosis.

What are the phases of the cell cycle?

Interphase (G1, S, G2), Mitosis, and Cytokinesis.

What occurs during the G1 phase of the cell cycle?

Growth and increase in cytoplasm and organelles.

What happens during the S phase of the cell cycle?

DNA replication occurs to ensure new cells have equal amounts of DNA.

What is the result of mitosis?

Two genetically identical daughter cells are produced.

What are sister chromatids?

Two identical halves of a duplicated chromosome joined at the centromere.

What happens during prophase of mitosis?

Chromatin supercoils into chromosomes, the nuclear membrane breaks down, and centrioles move to opposite poles.

What occurs during metaphase of mitosis?

Chromosomes line up at the metaphase plate, and microtubules attach to centromeres.

What happens during anaphase of mitosis?

Sister chromatids are separated and move to opposite poles.

What is cytokinesis?

The division of the cytoplasm between two daughter cells.

What is the difference between mitosis and meiosis?

Mitosis produces two identical daughter cells, while meiosis produces four genetically unique gametes.

What is the diploid number of chromosomes in humans?

46 chromosomes (2n=46).