Structure and Diversity of Cells Flashcards
What are the three major points of the cell theory?
- All organisms are composed of one or more cells
- The cell is the structural and functional unit of life
- Cells can arise only by division of preexisting cells
What four basic macromolecules are cells comprised of?
- nucleic acids
- proteins
- lipids
- carbohydrates
What were the requirements for the formation of the first cells?
- organic molecules (carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulphur)
- molecules for catalysis of chemical reactions and self-replication
- a barrier between the internal cell environment and the external environment
What is the only molecule able to both catalyze chemical reactions and self replicate?
RNA
catalyzes chemical reactions with ribozymes
self replicates through nucleotide base pairing
Prokaryotic cells vs eukaryotic cells
Prokaryotes lack a nuclear envelope (no internal membranes)
Eukaryotes have a nucleus (do have internal membranes)
What kind of DNA is present in eukaryotic cells?
linear DNA
What is the function of mitochondria in eukaryotic cells?
Site of oxidative metabolism
What do lysosomes provide in eukaryotic cells?
specialized metabolic compartments for digestion of macromolecules
What do peroxisomes perform in eukaryotic cells?
Various oxidative reactions
What is the endoplasmic reticulum? What is its function?
An extensive network of intracellular membranes.
Functions in the processing and transporting of proteins, and the synthesis of lipids.
What is the function of the golgi apparatus in animal cells vs plant cells?
In animal cells: sorts and transports proteins destined for secretion and serves as a site for lipid synthesis.
In plant cells: synthesis of some of the polysaccharides that compose the cell wall.
What is the function of the cytoskeleton?
Provides the structural framework of the cell and it responsible for the movement of entire cells, as well as intracellular transport/positioning of organelles and other structures.
What is the cytoskeleton composed of?
Actin filaments, intermediate filaments, and microtubules
What are the three main tissue systems of plant cells?
- ground tissue
- dermal tissue
- vascular tissue
What are the five main tissue systems of animal cells?
- epithelial tissue
- connective tissue
- blood tissue
- nervous tissue
- muscle tissue
What do epithelial cells form? What is their function?
Form sheets that cover the surface of the body and line internal organs.
Specialized for protection, secretion, and absorption
What do connective tissues include?
Bone, cartilage, and adipose tissue.
What are fibroblasts?
A cell type that fill the spaces between organs and tissues in the body
What does blood tissue contain?
Red blood cells (erythrocytes) and white blood cells (granulocytes, monocytes, macrophages, and lymphocytes)
What is nervous tissue composed of?
Supporting cells and nerve cells, or neurons, which are highly specialized to transmit signals throughout the body.
What is muscle responsible for? What are the 3 types of muscle?
Responsible for the production of force and movement.
3 types: skeletal, cardiac, and smooth
What is bright-field microscopy? What does it require?
Light passes directly through the cell. Requires fixation (killing) of cells/tissues, cutting a thin cross section of tissue, and a variety of stains to provide contrast between subcellular organelles in order to be visualized.
What is phase-constrast and differential interference-contrast microscopy?
Optical systems that convert variations in density and thickness into contrast that can be seen in the final image without staining.
Allows visualization of living cells.
What is fluorescence microscopy used for?
It is a very sensitive method used to study intracellular distribution of molecules.
What is confocal microscopy? What is it used for?
A specialized form of fluorescence microscopy that allows for focus on a single plane in the specimen.
Provides a much sharper image, and multiple images can be reconstructed into a 3D image.
Transmission electron microscopy vs scanning electron microscopy
Transmission electron microscopy: passes a beam of electrons through a thinly sliced, fixed specimen to form an image on a fluorescent screen.
Scanning electron microscopy: electron beam reflects off sample surface - coated with metal.
What does differential centrifugation do? What is it used for?
Separates and isolates organelles (size and density) for use in biochemical studies
