Exam 3 Review Flashcards
The Calvin cycle takes place in:
The stroma
What happens during interphase?
Cellular organelles double in number, DNA replicated to produce 92 chromatids (still 46 chromosomes), and then protein synthesis occurs. The chromosomes are not visible and the DNA appears as uncoiled chromatin.
When grown factors (hormones) arrive from other cells it increases _____ and _____ concentrations. Cyclin then binds to Cdk which phosphorylates the Cdk, and Rb inactivates _____ by binding to it. Cdk is then activated by _____, and Rb becomes inactivated by _____. Rb then releases E2F so that it can turn _____ DNA replication genes.
Cyclin, E2F, E2F, dephosphorylation, phosphorylation, on.
Plasma membranes have a phospholipid bilayer studded with _____ _____.
Membrane proteins
What does it mean for membrane proteins to be integral or peripheral?
The proteins can be embedded or attached to the surface of the cell.
What are three things that the extracellular layer can do, and what is it generally made of?
Defines cell’s shape, act as first line of defense, and attach to other cells. It is made of secreted products from within the cell.
Fiber composite vs. ground substance
for all cells
Fiber composite is a long network of cross linked filaments embedded into stiff surrounding material called the ground substance.
Fiber composites resist _____ while the ground substance withstands _____ forces.
Tension (being pulled lengthwise), Pressing
Fiber composites are _____ as well as strong.
Flexible
What fiber composite do animal cells secrete and what does it provide for the cell?
ECM (extracellular matrix), structural support.
What is the fibrous protein of animal ECM dominated by?
Collagen protein
What does the ground substance surrounding collagen proteins in animal ECM contain and what does it consist of?
gel-forming proteoglycans that consist of a core protein attached to many polysaccharides.
What is a polysaccharide?
a carbohydrate (e.g. starch, cellulose, chitin, or glycogen) whose molecules consist of a number of sugar molecules bonded together.
Structure of ECM correlates with its _____ of _____.
Function of tissue
What is an Integrin and what do they do?
a cell surface protein that bind proteins to ECM and hold cells in place. Once bound, they transmit signals to inform the cell that it’s properly anchored.
What is the initial fiber composite secreted by a plant cell? What is the following fiber composite secreted by a plant cell and when does this secretion occur?
Primary cell wall is secreted in a young cell (a cell that is still growing) - Secondary cell wall is secreted in a mature cell (after cell has stopped growing)
Where/how are animal ECM proteins synthesized, processed, and secreted?
synthesized in rough ER, processed in the golgi apparatus, and secreted via exocytosis where they group and/or attach to form huge complexes.
What does the primary cell wall consist of?
long strands of cellulose bundled together to form cable-like structures called microfibrals. The microfibrals are cross linked via hydrogen bonds to other polysaccharide filaments.
What is the ground substance in a plant cell?
Pectins
Where are pectins synthesized in plant cells?
The rough ER and the golgi apparatus.
What is turgor pressure and what causes it?
Force exerted by cell against cell wall. Caused by osmosis pushing plasma membrane against the cell wall.
What helps young cells elongate and expand?
Expansis coupled with turgor pressure.
What is expansis?
Proteins secreted by young plant cells into their cell wall that disrupt hydrogen bonds that cross-link microfibrals in the cell wall and allow microfibrals to slide past one another.
Where is the secondary cell wall located?
Between the primary cell wall and the plasma membrane.
What is epithelia (plural)?
Animal tissue consisting of sheet-like layers of tightly packed cells that line organs, glands, ducts, or body surfaces.
What is lamella?
The central layer between plant cells that holds them together. Consists mostly of pectins.
In animals, what are the -membrane proteins- that allow for direct cell-cell attachment?
Tight junctions, Desmosomes, and gap junctions.
What are tight junctions?
They are membrane proteins that stitch together membranes to form a water tight seal or a barrier. The adhesions are weak and easily broken. They are dynamic and loosen/ tighten as needed.
What are desmosomes?
They are membrane proteins found in animal epithelia and certain muscle cells. They form bridges between anchoring proteins in adjacent cells and are reinforced by intermediate filaments attaching anchoring proteins to cytoplasm.
Cells adhere to other cells of the same tissue type during:
Selective adhesion
What are antibodies?
proteins produced by immune response that often bind to another protein and change their structure or interfere with their ability to interact with other molecules.
What are cadherins?
Type of cell-cell adhesion protein in animals (critical to desmosomes) that provide physical basis for selective adhesion in cells.
Channels within membranes of adjacent cells allow cells to communicate via diffusion of cytosolic ions and small molecules (ex. amino acids). What are these signals responsible for?
regulating gene expression, altering which proteins are/not produced, activate/inactivate proteins within cell.
How do animal cells communicate? How do plant cells communicate?
Animal cells: gap junctions - directly connects cytosol of adjacent cells that allows for rapid passage of water, ions, or small molecules.
Plant cells: Plasmodesmata - membrane lined tubular gaps in cell walls through which plasma membrane, cytoplasm, and smooth ER can directly connect.
What are the two independent corridors in plant cells that are separated by the plasma membrane? Can molecules move through these corridors without touching the membrane?
Symplast (continuous network of cytoplasm connected by plasmodesmata), and apoplast (region outside of plasma membrane consisting of cell walls, lamella, and air spaces. YES.
_____ and _____ allow adjacent cells to transmit information, like conversations between neighbors.
gap junctions and plasmodesmata.
Tyrosine kinase and G-protein – coupled receptors are found in a cells:
membrane
G-protein – coupled receptors are so named because they are receptors that bind to G-proteins. The “G” in G-protein stands for:
guanine (..-nucleotide binding proteins)
Name two examples of distant signaling molecules that impact target cells:
Hormones and Neurotransmitters
Signal receptors are _____. How do signaling molecules deliver their messages to the signal receptors?
proteins, signaling molecules bind to signaling receptors.
Lipid-soluble signaling molecules diffuse across the hydro_____ region of the membrane and enter the _____ of their target cells. The signaling receptors exist _____ the cell.
phobic, cytosol, inside
No matter the location, signal receptors are dynamic and the _____ of the cell can change over time, and receptors can be blocked by _____.
sensitivity, beta blockers
When a signaling molecule binds to a signal receptor, the receptor _____ changes.
structure
_____ _____ _____ is formed in the cytosol and transported to the nucleus, changing the activity of _____.
hormone-receptor complex, genes
Large of hydro_____ signaling molecules are lipid insoluble and most of them cannot pass through the membrane. The receptors for these signaling molecules are located where?
philic, plasma membrane (cell surface)
Hormones existing in the plasma membrane produce _____cellular signals and process them _____.
intra, indirectly
What does the signal transduction do?
it converts extracellular signals to intracellular signals
Messages transmitted from a hormone can _____ as it changes form, triggering larger responses from cells.
amplify
What are the two types of signal transduction and amplification systems?
G-protein coupled receptors and Enzyme linked receptors.
G-protein coupled receptors initiate the production of ___-cellular _____ _____ that amplify the signal.
intra-cellular, second messengers
How do enzyme linked receptors amplify a signal?
By triggering the activation of a series of proteins in the cell through the addition of phosphate groups.
How is G-protein activity regulated? Explain how they are activated/inactivated.
Regulated by guanine nucleotide. Various proteins are activated by binding guanosine triphosphate (GTP) and inactivated when GTP is hydrolized to GDP. When G-protein is activated it triggers production of second messengers.
what are second messengers?
not proteins, they are small ions or molecules produced when GTP is activated, they diffuse rapidly and are produced quickly in large amounts. They are not restricted to a single role.
Why does GTP have more potential energy than GDP?
Three phosphate groups have four negative charges close together.
