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Week 3
Lecture 4
44
Anatomy
Undergraduate 2
09/26/2014

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Term
What is the cell life cycle?
Definition
interphase and cell division
Term
What are the phases of interphase?
Definition
G1
S
G2
Term
What happens in the G1 phase of interphase?
Definition
synthesis of proteins and centriole replication
Term
What happens in the S phase of interphase?
Definition
DNA replicates itself
Term
What happens in the G2 phase of interphase?
Definition
synthesis of machinery necessary for cell division and the centrioles completely "mature"
Term
What happens if a cell does not proceed to cell division?
Definition
it stays in the G2 phase
Term
What happens during DNA replication in the S phase?
Definition
exact replication of the DNA of parent cal to distribute to its daughter cells
Term
What is semiconservative replication?
Definition
each strand of existing DNA serves as a template for replication of a new strand of DNA and at the end of the replication process, two double helix strands have been formed from the original DNA
Term
What happens during the first step of semiconservative replication?
Definition
at specific recognition sites along the DNA molecule, helicase enzymes unwind and separate the two strands of DNA
Term
What is helicase?
Definition
enzyme the unzips the DNA double helix
Term
What happens during the second step of semiconservative replication?
Definition
as the DNA polymerase enzymes synthesize new strands of DNA off of the existing strands; replication begins with the formation of an RNA primer, performed by a primase enzyme
Term
What is DNA polymerase?
Definition
enzyme that makes a new DNA molecule by using the original molecule as a template
Term
What is primase enzyme?
Definition
type of RNA polymerase which creates an RNA primer
Term
What happens during the third step of semiconservative replication?
Definition
ligase enzyme ties together the fragments of the lagging strand to complete continuity of the replicated DNA; histone proteins reconfigue around the newly duplicated DNA
Term
What is ligase?
Definition
enzyme that catalyzes the linkage between two free ends of double-stranded DNA chains by forming a phosphodiester bond
Term
What is a consequence of DNA having a specific polarity?
Definition
the DNA polymerase can only synthesize in one direction, therefore where the polymerase is synthesizing smoothly and continuously, this strand is synthesized quicker; on the other strand, the enzyme must move the opposite way and as a result this enzyme must synthesize a chunk, move on, synthesize, and so on
Term
What is the leading strand?
Definition
strand that replicates nucleotides one by one and quicker than the other strand
Term
What is the lagging strand?
Definition
strand that replicates nucleotides in small segments and a little slower than the other strand
Term
What are Okazaki fragments?
Definition
short, newly synthesized DNA fragments that are formed on the lagging template strand and are eventually tied together by ligase enzymes
Term
What is chromatid?
Definition
each of the two threadlike strands into which a chromosome divides longitudinally during cell division
Term
What are the steps of mitosis?
Definition
prophase
metaphase
anaphase
telophase [cytokinesis]
Term
What happens during prophase?
Definition
-organization of mitotic spindles
-centrioles separate
-extend microtubules
-microtubules attach to kinetochore of centromere
Term
What is a kinetochore?
Definition
unique sequence of DNA bound to protein nuclear membrane fragments
Term
What happens during metaphase?
Definition
-chromosomes align in center
-microtubules extend from kinetochores of centromeres of chromosome to centriole on each side
Term
What happens during anaphase?
Definition
-separation of sister chromatids as they are "pulled" by microtubules
Term
What happens during telophase?
Definition
-uncoil chromosomes
-reform nuclear membrane around daughter chromosomes
Term
What happens during cytokinesis?
Definition
cell membrane divides into two daughter cells
Term
How is mitosis controlled?
Definition
-surface to volume ratio
-contact inhibition
-regulatory proteins
Term
How does the surface to volume ratio control mitosis?
Definition
critical cell size, and inadequate meeting of nutritional needs
Term
How does contact inhibition control mitosis?
Definition
stops proliferation
Term
How do regulatory proteins control mitosis?
Definition
proteins whose concentrations and/or activity increase/decrease throughout the cell cycle to effect preparation and execution of cell division
Term
What role do cyclins play in how regulatory proteins control mitosis?
Definition
initiates mitosis
Term
What are the two proteins that act as regulatory proteins in order to control mitosis?
Definition
cyclin and cyclin dependent kinase (CDK)
Term
What is a gene?
Definition
a segment of DNA which serves as the blueprint for a single polypeptide
Term
What are amino acids made of?
Definition
three sequential bases
Term
What is transcription?
Definition
the synthesis of mRNA from DNA template in order to transfer info from DNA to RNA
Term
Where does transcription occur?
Definition
in the nucleus
Term
What is translation?
Definition
the synthesis of a protein off of an mRNA template; uses mRNA, tRNA, and ribosomes
Term
Where does translation occur?
Definition
in the cytoplasm
Term
What happens in transcription?
Definition
DNA molecule is unzipped and RNA polymerase synthesizes mRNA through complementary base pairing
Term
What is a codon?
Definition
three sequential bases that will ultimately code for an amino acid
Term
Is the synthesized product of transcription the final mRNA product?
Definition
no, it still needs to be edited or shortened
Term
What are introns?
Definition
"non-informational" regions on the pre-mRNA that will be edited out
Term
What are exons?
Definition
"informational" regions on the pre-mRNA that will be spliced in to the final mRNA product
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