Molecular and Cellular Biology Flashcards

Question

Water Movement

Answer 1

osmosis- passive diffusion of water from high water (low solute) to low water (high solute) aquaporins- channels that mediate this water is polar and reacts with solutes like polar molecules, sugars, and proteins so solute conc. or osmolarity impacts water mvmnt as solute conc inc. water potential (free water molecules in solution and tendency for them to move into a solution decreses) solution is hypotonic: if cell is placed in solution with greater water potential than the water potential of the cell and is no movement of water into the cell -cell will expand and burst (plasmoptysis) solution is hypertonic: cell placed in solution with less water potential than water potenial of the cell, and is no net movement of water out of the cell -then cell will shrink (plasmolysis)

Answer 2

using ATP bring large materials (organic) and excrete waste via these processes large particle binds to surface receptors on cell surface and plasma membrane forms around it and engulfs it in vesicle within the cell Phagocytosis: cell ingests large particles pinocytosis: ingested material is liquid or macromolecules in dissolved in liquid Exocytosis: molecules released are carried to the cell surface in a secretory vesicle -the vesicle fuses with cell membrane and forms a pore thru which molecules are released

Answer 3

must respond to other cells and environmental changes medicated by cell surface proteins or receptors allow cells to communicate with molecules, tissues, cells outside plasma membrane homeostasis (allows cell to fn properly) must be regulated which is done by feedback mechanisms which detect changes and respond by inc or dec variable negative feedback: variable inc and response is to dec, example: temp, hormones positive feedback: more common, ex: blood clotting signaling molecules released and recognized which is mediated at cell membrane where signaling molecules binds to cell surface receptor the binding of this molecules triggers signal transduction cascade that leads to change in target molecule, rxn, or process

Answer 4

inc in body temp leads to release of neurotransmitters | this message reaches brain and activates sweat glands

Answer 5

cell division: pass genetic info from parent to daughter cells prokaryotes: DNA is copied, parent cell splits into 2 daughter cells (binary fission) eukaryotes: DNA wrapped around histones and packed into chromosomes and housed in nucleus DNA of eukaryotes divides by mitosis (non reproductive cells) or meiosis (reproductive) Interphase- first stage -G1: growing, genes into mRNA and then to protein -S: 2 copies of each chr made -G2: chr condense, mitochondria replicate, microtubules made M: prophase, metaphase, anaphase, telophase cytokinesis: final stage

Answer 6

Mitosis - chr replicate in interphase and are made of 2 genetically identical sister chromatids - in mitosis they are divided to form 2 daughter cells - parent cell diploid and therefore so is each daughter - meiosis -4 haploid cells within one set of chr prophase: chr coil and thicken, become shorter (condensation) - nuclear envelope starts to degrade - in animal cells 2 centrosomes (each have 2 centrioles) migrate to oppo sides and this forms mitotic spindle (network of microtubules) - 2 sister chromatids- attached by centromere (2 kinetochores) metaphase: microtubules from one centriole attach to kinetochore of 1 sister chromatid and fibers from other centriole attach to other one - fibers draw chromosomes to middle and align them along cell plate anaphase; spindle pull sister chromatids apart and to oppo poles of the cell telophase: mitotic spindle degrades and each set of chromosomes become surrounded by nuclear envelope, chromosomes decondense (uncoil) cytokinesis: in animal cell actin filaments contract to form cleavage furrow, pinches inward till cytoplasm divides and cell is cleaved into 2 daughter cells

Answer 7

formation of gametes and fusion to form zygote egg or sperm (1n) and zygote (2n) interphase precedes just like in mitosis prophase 1: chromosomes adhere to form homologous pairs (tetrads) and non sister chromatids exchnage info in crossing over metaphase 1: tetrads migrate metaphase plate and spindle fibers attach to centromeres of each chr anaphase 1: homologous chr are pulled apart and to oppo poles telophase 1: cytokinesis occurs and 2 daughter cells form prophase 2: new spindle forms metaphase 2: new microtubules fibers attach to centromeres, and make chr align in center of cell anaphase 2: sister chromatids divided telophase 2: nucleur envelopes reform to enclose 4 sets of daughter chromosomes cytokinesis: division of cytoplasm results in 4 haploid gamete cells

Answer 8

ensure cell division occurs under favorable conditions G1 checkpoint: cell commits to division or not, will not enter S phase if not large enough, limited nutrients, too crowded by others, lacks environmental signals, DNA damage after G1 checkpoint begins replication of DNA G2 checkpoint: if DNA damaged or not completely copied repair will be done, if repaired will go to mitosis, if not cell will self destruct

Answer 9

single or 2 ringed organic molecule with nitrogen sugar w/ 5 carbons phosphate group nucleotides joined by dehydration rxns that bind sugar molecule of one nucleotide to the phosphate group of another nucleic acid nitrogenous bases extend from backbone backbone on outside an bases on inside

Answer 10

RNA single strand DNA double helix RNA -AUCG DNA- ATCG

Answer 11

A-T and C-G and also A-U

Answer 12

DNA coild around histones nucleosome: 150-200 nucleotides around 8 histones telomere- at ends of chromosomes, repeated DNA seq chromosomes easily packaged into nucleus not strands centromere: center of chromosomes, sister chromatids joined by this

Answer 13

applies to prokaryotes and eukaryotes DNA formed from 2 comp strands phosphate group at 5' end and 5 carbon sugar at 3' end Steps: 1. helicase separates 2 strands and forms replication fork 2. leading strand (3 to 5)and lagging strand (5 to 3) 3. enzyme attaches a primer to leading strand 4. DNA polymerase catalyzes addition of nucleotides to leading strand in comp pairing, works toward fork 5. strand grown in 5 to 3 direction 6. as DNA molecule is unzipped by helicase the lagging strand is built in segments 7. primer is attached to lagging strand at fork and comp strand is made in 5 to 3 direction moving away from fork 8. DNA ligase joins segments

Answer 14

in cytoplasm for prokaryotes and nucleus for eukaryotes 3 steps Initiation: RNA polymerase binds to promoter and pulls strands apart and begins to make strand of RNA comp to template strand of DNA Elongation: growth of mRNA, RNA polymerase adds comp. RNA nucleotides to growing single strand of mRNA in 5 to 3 - the oppo strand of original gene is coding strand - mRNA will have same nucleotides as this strand except uracil Termination: RNA polymerase reaches sequence of DNA that makes enzyme release itself and stop transcribing

Answer 15

exons: coding introns: noncoding Steps: 1. cap added to 5 prime end of RNA (methylated guanosine triphosphate) 2. adenine nucleotides added to 3 prime end 3. enzyme called poly(A) polymerase catalyzes addition of the poly A tail (polyadenylation) 4. 5 prime cap and poly A tail protect RNA from degrading 5. introns removed 6. exons joined

Answer 16

synthesis of amino acids called a polypeptide takes place in cytoplasm of prokaryotes and eukaryotes mRNA processed in nucleus of eukaryotes first then transported across nuclear envelope ribosomes join amino acids into polypeptide chain ribosomes are made of protein and rRNA each ribosome has small and large subunit Steps: 1. mRNA transcript binds to short piece of rRNA on small subunit 2. next to this are A, P, and E sites that binds tRNA 3. tRNA carries anticodon which is comp to codon of mRNA 4. anticodon read via enzymes which attach amino acid to proper tRNA 5. start at AUG codon 6. tRNA has UAC anticondon that carrier methionine which binds and starts initiation 7. in elongation tRNAs bind to comp mRNA codonds 8. new tRNA anticodon binds at A site 9. at P site each new amino acid is joined by peptide bond 10. tRNAs released at E site 11. translocation refers to process by which mRNA advances on the ribosome by revealing next codon and letting tRNA bind and add its amino acid 12. termination is when machinery reaches stop codon 13. translation stops and chain is released from tRNA 14. ribosome splits into subunits and leaves mRNA

Answer 17

where transciption starts on the operon where RNA polymerase binds activators bind to turn transcription ON operator is next to promoter repressors bind to operator and block RNA polymerase from binding from reaching promoter and therefore turn transcription OFF

Answer 18

transcription factors bind to activate transcription in a sequence of DNA nucleotides called an enhancer located far from promoter

Answer 19

proteins that bind DNA and influence whether RNA polymerase binds a promoter and transcribes gene

Answer 20

a collection of genes transcribed and translated in a cluster

Answer 21

epigenetics: study of gene regulation and changes in an organism that result from this regulation (gene expression/) modifying gene expression can lead to phenotypic variations, not caused by mutations or changes in sequence of DNA nucleotides

Answer 22

only a small number of the genes carried by a cell are expressed by that cell unspecialized into specialized cell signals control this could be external (chemical) or internal (transcription factor)

Answer 23

differentiate into specialized cells adult vs embryonic adult: found in specific organ or tissue and gives rise to cells of that organ or tissue stem cell can be described by its potency - totipotent: into all cells and therefore can produce all structures, tissues, and organs - pluripotent: any cell except those with placenta - multipotent: into several cell types - oligopotent: only a few cell types - unipotent: only one cell type

Answer 24

mistakes during DNA replication chemicals or radiation (mutagens)- small scale recombination- large scale translocation (type of recombination): segment of DNA moves from one position to another on same chr

Answer 25

Point mutation- single base change, happen thru single base sub, insertion, or deletion base substitution can lead to - missense mutation: one amino acid is substituted for another - nonsense: substitution causes codon to be changed to stop codon - silent: changes in non coding region so no change insertion- base added deletion: base lost frame shift: adding or removing nucleotides changes total amt of DNA chromosome inversion: a break occurs and fragment breaks away and flips around then reattaches

Answer 26

germline: mutations in a cell that will become a gamete and these can be passed on somatic: body cell and cannot be passed on

Answer 27

used to separate and learn size of proteins, RNA or DNA 1. gel placed in salt solution 2. fragments loaded at top of gel 3. electrical field applied 4. salt solution conduct electricity and draws DNA to bottom of gel 5. DNA and RNA are neg charged so are drawn to positive charge at bottom 6. shorter fragments make it thru gel more quickly 7. fragments separated by size

Answer 28

optical microscope (light)- focuses visible light or UV thru series of magnification lenses to view specimen electron microscope: magnify even smaller cells, structures, or particles - use beam of electrons which are passed over surface of cell or structure - electrons reflected back and used to capture 3D image

Answer 29

study of how much light molecule absorbs tendency of molecules to be light absorbing or transmitting can be used to learn use spectrophotometer- passed stream of photons thru sample, some will be absorbed and reduce intensity of the light so conc of molecule is the diff in the intensity of light before passing thru sample and after light transmitted by spectrophotometer is of a certain wavelength electromagnetic spectrum - describes various wavelengths of electromagnetic radiation

Answer 30

to identify order of A, T, C, and G before DNA can be sequenced has to be amplified amplification: make copies of DNA and PCR used to amplify 3 Steps of PCR 1. segment of DNA is denatured with heat 2. short segments of comp DNA primers anneal to separated DNA strands 3. DNA polymerase makes new double stranded DNA

Answer 31

the process of transferring a functional gene into the cells of a patient to treat or prevent a disease by replacing defective gene can also be used to silence or knock out a gene or introduce new gene into the cells to fend off disease

Answer 32

take a cell, cell product or entire organism and make genetically identical copies of the original gene cloning: to clone and analyze segment of DNA the fragment is ligated to a cloning vector--a plasmid, and then inserted into a host, as vector replicates inside host the DNA is replicated reproductive cloning: organism in cloned and nucleus of adult is removed from that cell and inserted into enucleated egg cell, the cell is stimulated to form embryo which becomes blastocyst which will be implanted into mother, the offspring will be a reproductive clone therapeutic cloning: follows above process until blastocyst, then embryonic stem cells are extracted, grown, and induced to differentiate into specific cell type

Answer 33

manipulate genetic info of cell or organism involved taking gene or sequence from one organisms and introducing this foreign DNA into another the splicing of the DNA and reinsertion is done via restriction enzyme the enzymes recognize short symmetrical specific seq of DNA and cut at those sites -cuts result in blunt ends which terminates the base pair and cannot easily join other DNA -or sticky ends in which can be joined to another segment of DNA with comp sticky ends genetic engineering confers new property of an organisms and passes it on, this is called transgenesis

Molecular and Cellular Biology Flashcards

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