2.2 parts of cells Flashcards

Question

describe prophase

Answer 1

_Early Prophase:_ - chromosomes become visible - each w/ two chromatids joined at **centromere** - Centrosomes separate and **migrate** towards opposite poles - mitotic spindles and asters form _Late Prophase_ - nuclear envelope gradments - asters separate and goes to diff poles - **kinetochore microtubules** attach to kinetochore of **centromeres** and draw them towards the equator of the cell - **Polar microtubules** assist in forcing poles apart \*centrosome and aster are like same thing

Answer 2

- organization of chromosomes along metaphase plate - have enzyme separase that cleaves sister chromatids at the centromere \*separase cleaves sister chromatids at centromere

Answer 3

Separation of sister chromatids becoming daughter chromosomes

Answer 4

Nuclear envoleope starts to reform Nucleolus reforms chromosome losen up Get a cleavage furrow, contractile elements pull membrane in to get final cleavage (cytokinsis, breaks cells into their own cells)

Answer 5

- surface-to-volume ratio of cells (as cells get bigger it promotes cell division) - protein mediators: for example **cyclins** and **cyclin-dependent kinases** - Checkpoint 1 (g1): critical in determining progression (if not progress then it goes to G0) - Checkpoint (G2): requires critical threshold amount of M-phase promoting factor (MPF) to move to next stage

Answer 6

- Chemical signals: such as growth factors and hormones - Contact inhibition: Cell-to-cell contact can prevent cell division \*cells that dont follow rules can lead to cancer, contact inhibtion is removed when cell is damaged

Answer 7

- mRNA: carries genetic info from DNA in nucleus to ribosomes in Cytoplasm \*has 5' cap, poly-A-tail, - tRNA: bound to amino acids base pair with the codons of mRNA at the ribosome to begin process of protein synthesis \*top end has the aa to elongate the polypeptide that corresponds with anticodon sequence on the tRNA - rRNA: structural component of ribosomes \*has a large and small subunit \*nucleolus is associated with generation of rRNA\< because so much transcription to make RNA nuceolus is darker region

Answer 8

- promotes loosening of histones from DNA in area to be transcribed by binding to the **promoter region** - mediates the binding of **RNA polymerase** II to the promoter - **RNA polymerase** uses RNA triphosphates as substrates on the template stand - piece of DNA not used as template is the **coding trand** because the mRNA to be build will have th esame coded sequence - **TATA box** is the point of initiation of transcription

Answer 9

1. Initiation: Binding of RNA Pol II 2. Elongation: RNA Pol II elongates 3. Termination

Answer 10

Part of initiation - HAT can come in and acetylates the histones, this losens the binding of the histones to DNA - Can also have chromatin remodeling complex that can come in to losen DNA \*two ways to initiate gene transcription

Answer 11

- enhancer and promoter region are not lcose together, but when soemthing bidns to enhancer region DNA can bend and twist to get the enhancer region close to start site RNA pol binds to DNA\< separates and makes a copy of the template trans Signma factor helps to enhance the specificity of the interaction Improves function of RNA pol Makes copy of tempplate strand? Double check that

Answer 12

RNA polymerase with sigma factor goes along ang elongates the RNA transcript - Uracil is incoorperated instead of Thymine - transcrription occurs in mitochondira - mRNA is processed by: 5' cap, poladenylation and splicing Now have this RNA refered to pre mRNA\< must modifty so that you can make proteins Exons and introns (spacers need to be removed) Splicing event with splicosomes Poly A trail and guanine cap Mol then transported out of nucleus and into sytosol

Answer 13

1. initiation * Leader sequence on mRNA (AUG) attaches to the small riosomal unit, methionine charged initiator tRNA binds to the small subunit * Small ribosomal subint interacts with AUG at the P site * Start codon then recognized by anticodon and will bind to P site * Use GTP as energy source, phosphorlyation to prep for protein translation * Large subunit comes in (have fmet trna, large and small -\> forms initiation complex) 2. Elongation * at A site get a new tRNA binding a specific codon on the mRNA mol * robosome moves down mRNA mol, metis removed from previous tRNA a the E site, and then A site is reopened * note can have multiple ribsomes interacting on the rna mol 3. Termination * When encounters stop codom

Answer 14

1. mRNA ribosome complex is directed to the rough ER by SRP. * SRP binds to receptor site 2. SRP is released and the growing polypeptide snkaes through the ER membrane pore into the cisterna 3. the signal sequence is clipped off by an enzyme. as protin syn cont, sugar groups can be added to the protein 4. in this ex, compelted protein is released form risocome and folds into 3d confomation aided my chaperone mol 5. protein is enclosed within a protein (coatomer) coated transport veiscle. * vesicle can make its way to golgi for further protein processing

2.2 parts of cells Flashcards

(38 cards)