Cell Biology and Genetics: Microscopy, Cell Types, and DNA Structure

What is the definition of a cell?

A cell is the basic structural and functional unit of any living organism.

Who coined the term 'cell'?

Robert Hooke, in his work 'Micrographia' (1665).

What does the Latin word 'cellula' mean?

Small room.

What is cytology?

The study of cells.

What type of microscope is used for a wide range of magnifications up to 1000x?

Light microscope.

What are the two types of microscopy that require a visible or UV light source?

Fluorescent microscopy and light microscopy.

What is the purpose of the excitation filter in fluorescent microscopy?

To allow only specific wavelengths of light to excite the fluorescent sample.

What is the difference between excitation and emission energy in fluorescent microscopy?

Excitation energy is always higher than emission energy.

What is a key feature of confocal fluorescent microscopy?

It scans small sections of the sample with a laser to generate sharper images.

What is the primary function of transmission electron microscopy?

To shoot electrons through thin specimens stained with electron-dense heavy metals.

What is the main advantage of scanning electron microscopy?

It provides 3D visualization of surface structures.

What does the term 'cell evolution' refer to?

The concept that all cells evolved from one or a few ancestral cells.

Which microscope uses a laser to excite a specimen?

Confocal microscope.

What is the role of a dichroic mirror in fluorescent microscopy?

It separates the excitation and emission light paths.

What type of samples can be used in fluorescent microscopy?

Alive or fixed samples with fluorescent proteins or dyes.

What is the purpose of staining in transmission electron microscopy?

To enhance contrast by using heavy metals.

What is the magnification range of light microscopy?

From 1000x down to 200 nm.

What is the significance of the term 'micrographia'?

It refers to the detailed observations of minute bodies made by magnifying glasses.

What are the two main types of prokaryotic cells?

Bacteria and Archaea.

What is the advantage of having organelles in eukaryotic cells?

Organelles allow for compartmentalization of functions, increasing efficiency.

Who was the first to observe microorganisms?

Antonie van Leeuwenhoek

What term did Antonie van Leeuwenhoek use to describe microorganisms?

Animalcules

What are the two main types of cells?

Prokaryotic and Eukaryotic

What does 'Pro' in Prokaryotic mean?

Before

What does 'Eu' in Eukaryotic mean?

Well, true, good

What does 'Karyon' refer to in cell biology?

Nut, kernel, nucleus

What are the three domains of life?

Bacteria, Archaea, Eukaryotes

What is the central dogma of molecular biology?

The flow of genetic information in cells

What is the role of the nucleus in a eukaryotic cell?

Control of cellular activity through regulation of gene expression

What is the function of mitochondria?

Generation of energy in the form of ATP via oxidative phosphorylation

What does the smooth endoplasmic reticulum (ER) synthesize?

Lipids and steroid hormones

What is the primary function of rough endoplasmic reticulum (ER)?

Protein synthesis, translocation, folding, glycosylation

What is the role of the Golgi complex?

Protein modification through glycosylation and synthesis of glycolipids

What do endosomes do in a cell?

Sort proteins between endocytic and exocytic traffic

What is the function of lysosomes?

Degradation and turnover of organelles (autophagy)

What is the role of peroxisomes?

Synthesis and degradation of hydrogen peroxide and oxidation of fatty acids

What is the cytoskeleton's function?

Provides cell structure and allows movement

What is cytoplasm?

Cellular content within the plasma membrane and outside the nucleus

What is cytosol?

Content of the cytoplasm excluding membrane-bounded organelles

What is the function of the plasma membrane?

Serves as a barrier, provides structure, and controls transport

What is the nucleolus responsible for?

Ribosomal assembly

What is the function of centrioles?

Spindle formation and flagellum/cilium formation

Which organelle does not have a membrane?

Centriole

Which organelle has a single membrane?

Chloroplast

What is the Golgi apparatus?

A membranous organelle involved in modifying, sorting, and packaging proteins and lipids.

What is the significance of endomembrane compartmentalization in eukaryotic cells?

It allows for the separation of cellular processes and the formation of specialized organelles.

How did mitochondria and plastids originate?

They originated from primordial symbiotic relationships between an anaerobic archaea and an aerobic prokaryotic symbiont.

What is hypothesized about the evolution of endomembranous organelles like the ER and Golgi?

They are thought to have evolved through endogenous membrane invaginations.

What are the four major macromolecules that serve as building blocks for cellular content?

Carbohydrates, proteins, lipids, and nucleic acids.

What orientation are DNA and RNA synthesized in?

They are synthesized in the 5' to 3' direction.

What are nucleotides used for besides being building blocks of nucleic acids?

They are also used as energy carriers (e.g., ATP) and coenzymes.

How are proteins made from RNA?

Proteins are synthesized through the processes of transcription and translation of RNA.

What gives proteins their unique properties?

The sequence and composition of amino acids in the protein determine its properties.

What are some cellular uses of lipids?

Lipids are used for energy storage, membrane structure, and signaling.

What is the atomic mass unit (amu)?

A unit of mass used to express atomic and molecular weights.

What is Avogadro's number?

6.02214076×10²³, the number of elementary entities in one mole of a substance.

What is the octet rule?

Atoms are more stable when their valence shell contains eight electrons.

What are covalent bonds?

Bonds formed by the sharing of electrons between atoms.

What determines the polarity of a covalent bond?

The difference in electronegativity between the bonded atoms.

What are noncovalent hydrogen bonds?

Electrical attractions between oppositely charged atoms from different molecules.

What are ionic bonds?

Electrostatic attractions between oppositely charged ions.

What are van der Waals forces?

Weak, nonspecific interactions caused by fluctuations in electron distribution.

What are organic molecules?

Molecules that contain carbon and hydrogen, often with other elements.

What are the four major types of organic molecules important for cellular functions?

Carbohydrates, proteins, lipids, and nucleic acids.

What is the role of messenger RNA (mRNA)?

It transcribes the genetic code from DNA for protein synthesis.

What is the role of transfer RNA (tRNA)?

It translates the genetic code into amino acid sequences during protein synthesis.

What is the role of ribosomal RNA (rRNA)?

It forms the structural and functional core of ribosomes.

What is a phosphodiester bond?

A bond that links the sugar and phosphate groups in the backbone of nucleic acids.

How many amino acids are commonly used to build proteins?

There are 20 standard amino acids.

What is the significance of the N-terminus and C-terminus in proteins?

They indicate the directionality of the protein chain, from amino group to carboxyl group.

What are monosaccharides?

The simplest form of carbohydrates, consisting of single sugar units.

What are glycosidic bonds?

Covalent bonds that link monosaccharides to form disaccharides and polysaccharides.

What are the two main types of polysaccharides used for energy storage?

Starch (in plants) and glycogen (in animal cells)

What is the primary structure of starch?

A polymer of glucose with amylose (20-30% unbranched) and amylopectin (70-80% branched)

What type of glycosidic bonds are found in amylose?

α(1→4) glycosidic bonds

What type of glycosidic bonds are found in amylopectin?

α(1→4) and α(1→6) glycosidic bonds

What is the structure of cellulose?

A linear polymer of glucose with β(1→4) glycosidic bonds

What is chitin?

A linear polymer of N-Acetylglucosamine (GlcNAc) found in insect exoskeletons and fungal cell walls

What are the main functions of carbohydrates in cells?

Energy source, long-term storage, and mechanical support

What are glycoproteins and glycolipids involved in?

Intracellular signaling, cell surface receptor interactions, and adhesion

What is the role of fatty acids in energy storage?

Stored as fat droplets of triacylglycerols, providing 6 times more energy per weight than sugars

What is the structure of phospholipids?

Amphipathic molecules that form bilayers in cell membranes

What is the significance of saturated vs unsaturated fatty acids?

They affect membrane packing and fluidity

Who were the key scientists in discovering the structure of DNA?

Rosalind Franklin, Maurice Wilkins, James Watson, and Francis Crick

What is the basic structure of DNA?

A double helix with two strands twisted around each other

How are nucleotides linked in the DNA backbone?

Via phosphodiester bonds

What type of bonds link the two strands of DNA in the helix?

Hydrogen bonds

What is a gene?

The functional unit of heredity; a segment of DNA that carries instructions for making RNA

What is the human genome's approximate number of genes?

About 30,000 genes

What does a karyotype represent?

A visual representation of the number and appearance of chromosomes in a eukaryotic cell

What is a nucleosome?

The basic unit of eukaryotic chromosome structure, consisting of DNA wrapped around histones

What are histones?

Proteins that help package DNA into nucleosomes

What is the effect of histone acetylation on gene expression?

It neutralizes positive charges on histones, loosening chromatin structure and promoting gene expression

What is the difference between heterochromatin and euchromatin?

Heterochromatin is always condensed, while euchromatin is more open and accessible

What are the roles of structural maintenance of chromosomes (SMC) proteins?

They help maintain chromosome structure and organization during cell division

What is the relationship between genome size and organism complexity?

Genome size does not necessarily correlate with the complexity of an organism