Chapter 3: Cells and Tissues Flashcards
What form is DNA in when a cell is not dividing?
Chromatin
What form is DNA in when a cell is dividing?
Chromosomes
What is the name of proteins that chromatin is wound around?
histones
What are the three types of cell junctions?
Tight junctions, desmosomes, gap junctions
What are tight junctions?
impermeable junctions that encircle the cells and bind them together into leakproof sheets
What is the function of tight junctions?
to prevent substances from passing through the extracellular space between cells
What is the function of desmosomes?
They prevent cells subjected to mechanical stress (such as heart muscle cells and skin cells) from being pulled apart.
What is the structure of desmosomes junctions?
thickenings of adjacent plasma membranes (plaques) that are connected by fine protein filaments (made of cadherins). Thicker protein filaments extend from the plaques inside the cells to the plaques on the cells’ opposite sides
What is the function of gap junctions?
to allow communication
What is the structure of gap junctions?
hollow cylinders composed of proteins (called connexons) that span the entire width of the neighboring membranes (which are therefore called transmembrane proteins)
What type of molecules cannot move across gap junctions?
macromolecules
What are the three alternate types for the cell membrane junctions?
impermeable junctions, anchoring junction, communicating/transmembrane junctions
What are the three major components of cytoplasm?
cytosol, inclusions, organelles
What is the cytosol?
It’s a semi-transparent fluid that suspends the other elements (organelles, particles)
What is dissolved in the cytosol?
nutrients and other solutes
What are inclusions?
Inclusions are non-living chemical substances that may or may not be present, depending on the specific cell type. Most are stored nutrients or cell products floating in the cytosol.
What are examples of inclusions? (4)
lipid droplets, glycogen granules, pigments, mucus
What are organelles?
specialized cellular compartments that are the metabolic machinery of the cell
What are the protrusions within the second plasma membrane of mitochondria called?
cristae
What is the difference between ribosomes in the cytoplasm and the ribosomes stuck to the RER?
The ribosomes stuck to the RER produces proteins that functions outside of the cell
What is the structure of peroxisomes?
Membranous sacs of oxidase and catalase enzymes.
What is the function of peroxisomes?
The enzymes detoxify a number of toxic substances such as free radicals. The most important enzyme, catalase, breaks down
hydrogen peroxide
In what conditions do lysosomes (sacs that contain very powerful enzymes) burst?
when the cell is injured or deprived of oxygen and when excessive amounts of vitamin A are present
What is the structure of microtubules?
Cylindrical structures made of tubulin proteins.
What is the function of microtubules?
Support the cell and give it shape. Involved in intracellular and cellular movements. Form centrioles and cilia and flagella, if present
What is the structure of microfilaments?
Fine filaments composed of the protein actin.
What is the function of microfilaments?
Involved in muscle contraction and other types of intracellular movement; help form the cell cytoskeleton and microvilli, if present
what is the structure of intermediate filaments?
Protein fibers; composition varies.
what is the function of intermediate filaments?
The stable cytoskeletal elements; resist mechanical forces acting on the cell
What is the structure of centrioles?
paired cylindrical bodies, each composed of nine triplets of microtubules
what is the function of centrioles?
Organize a microtubule network during mitosis (cell division) to form the spindle and asters. Form the bases of cilia and flagella.
What is an example of cell that connects body parts?
fibroplast
erthyrocyte (RBC)
What is an example of cell that cover and line body organs
epithelial cells
What is an example of cell that moves organs and body parts
Skeletal
cardiac
smooth muscle cells
What is an example of a cell that stores nutrients?
fat cell
What is an example of a cell that fights diseases?
WBC
What is an example of a cell that gathers information and controls body functions?
nerve cell
What is an example of a cell that reproduces?
Oocyte
page 102
What is the segment of DNA where transcription begins and ends called?
Promoter and terminator
What is the function of mRNA?
directs the synthesis of proteins
What is the function of rRna?
joins with ribosomal proteins to make ribosomes
What is the function of tRNA
transfers amino acids
What is always the starting amino acid?
methionine
Which molecules are able to simply diffuse into a cell?
lipid-soluble small molecules
What molecules are eligible for carrier-mediated facilitated diffusion
lipid insoluble solutes
What molecules are eligible for channel-mediated facilitated diffusion
small lipid insoluble solutes
is glucose charges?
YES
What is the term used for when a vesicle enters a cell then promptly leaves it?
transcytosis
What is primary active transport?
An active process in which a substance moves across the membrane against its concentration gradient by pumps that use ATP for energy
What is secondary active transport?
Coupled active transport of two substances across the membrane using energy supplied by a Na+ or H+ concentration gradient maintained by primary active transport pumps. Where which antiporters move Na+ or H+ in different directions across the membrane, and symporters move Na+ and H+ in the same direction across the membrane
How long is G1 phase in mitosis?
8-10 hours
How long is the synthesis phase in mitosis?
8 hours
How long is the G2 phase in mitosis?
4-6 hours
What is another word for mitosis?
Somatic cell divison
Why is mitosis called somatic cell division?
Because it happens in somatic cells (all cells except for gametes)
In which mitosis step does cytokinesis happen with?
telophase
How many HOMOLOGOUS pairs of chromosomes do somatic cells have?
(depends on sex of individual) 22 homologous pairs, and 1 pair are sex chromosomes (xY or YY) for a total of 23 pairs
What is a hypertonic solution?
A solution that contains more solutes than inside the cell
What happens to a cell when it is placed in a hypertonic solution?
Cell begins to shrink
What is a hypotonic solution?
A solution that contains fewer solutes
What happens to a cell that is placed in a hypotonic solution?
they burst or lyse
What is filtration?
the process by which water and solutes are forced through a membrane
(or capillary wall) by fluid, or hydrostatic, pressure
What causes aging (rapid reproduction of a cell, part, or organism.)? (2)
• People under stress have shorter telomeres than others
• Free radicals and glycation of cellular structures
