bio 1 Flashcards
where is non nuclear DNA found? What are characteristics of it?
in mitochondria (mitochondrial DNA) . - haploid, from maternal copy - circular - helical -
what is the nucleolus?
site of rRNA transcription and ribosome assembly.
What is the rough ER?
ribosome covered ER that translocates proteins into the ER lumen to be translated.
-proteins from RER are bound to the ER itself, the golgi, the lysosome, the endosome, the plasma membrane or some to be secreted outside the cell
What is the smooth ER?
ER with no ribosomes- regulates and releases calcium ions and processes toxins + Lipid synthesis/ modifications NOT metabolization.
What is the golgi apparatus function?
cellular post office for protein; organize and continue post translational modifications, excrete vesicles bound for plasma membrane back to ER or to organelles.
What is the structure of the mitochondrion and function?
outer mitochondrial membrane- separates content of the mitochondrion from he rest of the cell and creates compartment with ideal conditions for aerobic respiration.
inter membrane space (between outer an inner membrane)- where protons are pumped by ETC- high proton concentration can easily be formed in chemiosomosis.
inner membrane space- contains electron transport chains and ATP synthase that carry out oxidative phosphorylation.
Cristae- tubular or shel like projections of inner membrane which increases available surface area for oxidative phosphorylation.
Matrix- fluid inside the mitochondrion contains enzymes for the Krebs cycle and the link reaction.
What does the endosymbiotic theory suggest?
mitochondria evolved form aerobic prokaryotes that were engulfed by larger host prokaryotes.
Evidence include: The presence of the double bilayer membrane, the fact that mitochondria have their own DNA, that they replicate their own DNA, and that they divide and replicate much like a bacterium
How do the pH values of the matrix and the inter membrane space compare?
the intermembrane space will be more acidic (lower pH) because of the hydrogen ion gradient across the inner mitochondrial membrane.
Predict the consequences of the insertion of hydrogen channels within either of the two mitochondrial membranes.
alternate pathway for their passageway back into the matrix (down their concentration and charge gradient) other than through the ATP synthase. This would decrease the production of ATP.
What is the role of the lysosomes?
pH5- digest cell parts and fuse with phagocytotic vesicles + can participate in cell death
What are peroxisomes?
Self replicating organelle that detoxify chemicals and participates in lipid metabolism.
1) A lab worker must inject a segment of DNA into the nucleus of a living cell. To access the nuclear lumen, the microscopic needle must pierce a minimum of how many layers of lipid membrane?
A) 2 B) 3 C) 4 D) 6
D) cell membrane (2), plus the outer nuclear membrane (2), plus the inner nuclear membrane (2), for a total of six single layers of lipids-
What are microtubules made of?
Tubulin; alpha and beta which forms a heterodimer that assembles into a long chain of protofilaments.
13 protofilament surrounding one hollow core = one microtubule
What is the 9+2 arrangement?
found only in eukaryotic cilia and flagella. The “9” and “2” refer to nine doublets (two microtubules each) surrounding a center doublet (2 microtubules) in a wheel-like design. That would be a total of 20 microtubules—each one of those twenty microtubules being the hollow tube of 13 protofilaments just described.
What is the cytoskeleton made of?
scaffolding like network of microfilaments, microtubules and intermediate filaments that provides structure to the cell and creates a highway of sorts for intracellular transport.
what are intermediate filaments?
proteins that polymerize to form filaments that are intermediate in diameter.
- Strength and structure
- Lamins and keratin
- Protect from shear stress
- Tend to be more structurally stable/ stronger filaments
- Organization and interaction
what are microfilaments?
proteins monomers (like actin) polymerize to form microfilaments and form the thin portion of sarcomere.
○ Gives cells their shape
○ Cell motility
what are thick filaments?
- microtubules
- Position organelles
- Direct transport
- Cilia and flagella= specialized cells for movement.
What is the difference between Flagella and cilia?
Flagella are whip-like projections from the cell body used for locomotion. In humans, sperm cells are the only cells that have flagella.
Cilia are similar protrusions found on the lumen-facing side of many epithelial cells lining various cavities in the body. In humans cilia are found in the lungs, ependymal cells of nervous system, and reproductive system.
Do all cilias contain microtubules? in flagella of sperm? in cells part of cytoskeleton? in spindle apparatus?
Yes to all
What problems would a disease that prevented microtubule production cause?
- weakened cytoskeleton
- weakened organelle motility/ transportation
- inability to complete metaphase of meiosis.
What are phospholipids
Phospholipids are lipid molecules with non-polar tail regions and a polar phosphate heads. This polarity is pivotal to their function in membranes.
- formed by combining a glycerol molecule with two fatty acids and one phosphate.
-
what are integral proteins?
proteins that have one or more moieties (i.e., segments) embedded within the phospholipid bilayer.
what are surface proteins?
aka peripheral proteins that do not enter the hydrophobic core but are contained entirely on the polar surface of the membrane.
what are transport proteins?
integral proteins that span the entire width of the bilayer membrane, creating tunnels for the passage of ions, proteins or other substances through hydrophobic core.
What’s a membrane receptor ?
A membrane receptor is any protein that specifically binds a signaling molecule to initiate a cellular response.
what’s cholesterol?
an amphipathic (hydrophilic and phobic) molecule with a steroid region and a polar region. It’s part of the fluid mosaic model of the plasma membrane.
How does high temperature affect cholesterol in the plasma membrane?
higher temperature around physiological temperature (37C), the non polar region (steroid region) interacts with the hydrophobic tail of the phospholipids of the plasma membrane and holds them in place—> increases rigidity.
How does lower temperature affect cholesterol in the plasma membrane?
he interactions between the non-polar tails could cause crystallization, the presence of the rigid steroid portion of cholesterol disrupts Van der Waals forces between fatty acid tails maintaining a minimum level of fluidity. –> makes it more fluid
What are the four types of membrane transport?
1) simple diffusion - no ATP
2) facilitated diffusion- no ATP (ex: osmosis)
3) Active transport (ATP Required) –> required to move something against its concentration gradient.
4) Secondary active transport –> no direct coupling of ATP required.
what are tight junctions?
limit passage of molecules and ions through the space between cells- Water proof barriers. Most often found in epidermis of the skin
What are gap junctions?
Tunnels between adjacent cells, allowing exchange between cytoplasm of cells.
ex: in heart cells
what are adherent junctions?
cell to cell junctions that keep cells together with cadherins.
–> prominent in actin cytoskeleton
What are desmosomes?
another type of cell-to cell junctions that attaches cells together.
Has intermediate filament, adhesion proteins (cadherins!) and anchor proteins.
How do cell communicate?
1) Endocrine- long distance signaling through hormones.
2) paracrine: local area signaling
3) autocrine: signal received by same cell that secreted it.
4) intracrine: intrasignaling within same cell
5) juxtacrine: contact dependent signaling
6) nervous system: synapses
What type of receptors are steroids?
intracellular receptors
What’s the general pathway of G proteins?
signal –> receptor –> G protein alpha and Beta unit–> GTP bind –> alpha unit dissociates and acts as agonist for another enzyme like adenylyl cyclase –> catalyzes conversion of cAMP through ATP to stimulate PKA production
in the cell cycle, what is G0?
non proliferative- cell arrest and death phase
fully differentiated. neurons and cardiac muscle cells are frozen in G0 and do not divide
in the cell cycle, what is G1?
Growth phase of cell- phase most active cells live and function
in the cell cycle, what is S?
DNA is replicated
in the cell cycle, what is G2?
Follows S phase and features continues cell growth and high metabolic activity- more dan replicated
what’s M phase?
mitotic division
what’s chromosome number ? haploid chromosome number ?
46; 23
what does mitosis yield?
2 genetically identical diploid daughter
what happens during prophase of mitosis?
During prophase, the nuclear membrane degenerates and the chromosomes condense.
what happens during metaphase of mitosis?
Metaphase is indicated by the chromosomes lining up at the metaphase plate and formation of the spindle apparatus.
what happens during anaphase of mitosis?
Anaphase is indicated by separation of the chromosomes and migration toward the opposite poles of the cell.
what happens during telophase of mitosis?
Telophase is indicated by the nuclear membranes beginning to re-form and the chromosomes unwinding.
what happens during interphase of mitosis?
resting phase between successive mitotic divisions of a cell, or between the first and second divisions of meiosis.
How are the cell cycle phases of meiosis (I and II) different from those in mitosis?
They are basically the same except crossing over happens during metaphase of meiosis and meiosis I yields two daughter cells with two homologs.
These two daughter cells then further divide into four daughter cells the are not genetically identical and each has one chromosome (n chromosome) while mitosis has 2n chromosomes.
What is chromosome nondisjunction and when does it occur?
Nondisjunction results in an unequal number of chromosomes in the daughter cells and happens during anaphase of meiosis I or II.
extra chromosome - tiresome
When does crossing over occur and why?
during meiosis I.
important because it breeds diverse beings and helps our species survive during natural selection
What is the yield of meiosis?
4 genetically distinct haploid daughters cells.
centromere splits during meiosis II.
2) A karyotype is somewhat like a photographic list of all of the chromosomes found in a cell. If homologous pairs are present, they appear next to one another on the exposed film. All of the chromosomes for the entire cell are presented on the same slide, making differences in the relative length, size and orientation of the chromosomes readily apparent. If a karyotype were produced for a human cell that had just undergone Telophase I of Meiosis, the entire karyotype slide should contain (assume that the chromosomes are still condensed and have not reverted back to chromatin):
A) 23 pairs of homologous chromosomes, all of similar size
B) 46 chromosomes, increasing in size from 1 to 23
C) 92 chromosomes, decreasing in size from 1 to 92
D) 23 chromosomes, decreasing in size from 1 to 23
d
