Mitosis, DNA/rna, Gene Expression, Gene Regulation

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Mitosis, DNA/rna, Gene Expression, Gene Regulation

Flashcards For BISC 160
Questions About Mitosis, DNA, Transcription And Translation, And Genes....

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What are double ringed nitrogenous bases called, and what are they?
Purines/ guanine and adenine
What are single ringed nitrogenous bases called, and what are they?
Pyrimidines/ cytosine and thymine (they all have ''y's")
What is the name of the rule that refers to the complementary nature of DNA? (Number of Adenine = Number of Thymine and Number of Cytosine = Number of Guanine)
Chargaff's Rule
The process of DNA making a copy of itself is called
Replication; average speed: 20 nucletides per second are added to new strand
When replication is completed, each molecule will have one original template strand. This is called
Semi-conservative replication
In DNA replication, new strands always begin at its __ end and nucleotides are added to its __ end.
5' , 3'
Enzymes responsible for building a DNA polymer; there are more than one kind; they catalyze the addition of nucleotides to the 3' end of the strand and cannot start the strand
DNA polymerases
Molecules in the nucleus that provide the substrates to build a new strand of RNA or DNA; have 3 phosphate groups
free nucleotides
Specific sequences on the DNA template strand where replication begins
origin of replication
Giant cloud of molecules that contain all enzymes, all substrates, and everything needed for replication --moves along the DNA molecules--replication only occurs where this is
DNA replication machine
Enzyme responsible for pulling the DNA helix apart; breaks hydrogen bonds
DNA helicase
Proteins that bind to the strands, keeping them apart so replication can occur
Single-strand binding proteins
Point where the two template strands of DNA are being pulled apart (y-shaped structure)
Replication fork
New strand built in the same direction that the replication fork is moving
Leading strand
New strand built in the opposite direction of the movement of the replication fork
Lagging strand
Built first, at the 5' end about 10 nucleotides long; synthesized at the point where replication begins
RNA primer
Responsible for building primers, made of RNA; digested and replaced with DNA nucleotides
Primase enzymes
Gets rid of primers and joins strands together
DNA ligase
100 to 2000 nucleotides pieces (short fragments of DNA) that must be joined by DNA ligase to form the lagging strand in DNA replication
Ogazaki fragments
A mistake that happens in replication
One molecule of DNA with proteins attached; organized into nucleosomes; condensed chromatin
Cells that lack membrane-bound organelles (no nucleus); generally have only ONE CIRCULAR CHROMOSOME; only one origin of replication (bidirectional); cell division is unique
Prokaryotic cells
Cells that have membrane-bound organelles, including nucleus; chromosomes are linear; more than one chromosome per nucleus (each species has a specific number of chromosomes)
Eukaryotic cells
Actual material in the nucleus; 40% DNA, 60% protein
Nonhistone proteins that help maintain chromosome structure
Scaffolding proteins
Structures of which the inside is made of 8 histone protein molecules; length of DNA (wrapped twice) is 146 base pairs long; positively charged
Two types of Eukaryotic Cells
Germ cells- very specialized cells involved in sexual reproduction   Somatic cells- majority of eukaryotic cells; nuclear division
Phase in cell division when chromatin is not condensed into chromosomes; no cell division; no nuclear division; majority of the time in the life of the cell
Phase in cell division when no DNA synthesis occurs; growth and metabolism take place; usually the longest phase
G1 phase (gap)
Phase in cell division when DNA replication occurs, chromosomes are duplicated
S phase (synthesis)
Phase in cell division when there is alot of protein synthesis; the cell gets ready for division
G2 phase (gap)
Phase in cell division when the nucleus divides; nuclear divison; cytoplasm divides (cytokinesis); forms two daughter cells
M phase (mitosis)
Nuclear division that produces two nuclei containing chromosomes identical to the parental nucleus; begins at the end of the G2 phase; occurs in 4 phases
1st stage of mitosis; nuclear membrane starts to fall apart; pieces are stored in vesicles (can be recycled); centrioles move up the sides; mitotic spindle forms
Identical, double-stranded DNA sequences; linked by cohesin (ring shaped protein)
Sister chromatids
Specialized constricted region of a chromatid; contains kinetochore (a multiprotein complex to which micrtotubules can bind)
2nd phase of mitosis; mitotic spindle is complete; sister chromatids line up at the midplane (metaphase plate)
Mitotic spindle's two types of microtubules:
Polar microtubules- run from the poles and overlap at the metaphase plate   Kinetochore microtubule- run from the micrtobule organizing centers and bind to the kinetochores of sister chromatids
Other type of mictotubule that runs from the centrioles toward the outside of the cell
Astral microtubules
3rd stage of mitosis; sister chromatids pulled apart; make daughter chromatids, which head to the poles; kinteochore MT get shorter and pull daughter chromatids in; polar MT get longer, pushing the 2 poles of cell apart; oblong mother cell with copy of each chromatid at each pole
Final stage of mitosis; nuclei are starting to reform; spindle fibers disintegrate; reforming nuclear envelope; chromosomes start to disorganize; cytokinesis begins
Division of the cytoplasm to yeild two daughter cells; IN ANIMALS- microfilaments pinch (cleave) cell and form 2 cells IN PLANTS- occurs intially by building cell plate at metaplate; new cell wall and plasma membrane BOTH- mitochondria and chloroplasts each copy itself and DNA
Why do somatic cells divide?
Growth Repair/replacement Maintenance NOT for sexual reproduction
What regulates the cell cycle?
Proteins (cyclins-regulatory proteins produced by cells); accumulation in cells

Cyclin-dependent kinases (cdks)- protein kinases involved in controlling the cell cycle
Sequence of the DNA molecules that holds the information to build a specific product (protein and RNA products)
A complex series of events in which the info in DNA directs production of specific proteins coded in genes
Gene expression
The process of building an RNA molecule that is complementary and antiparallel to a small portion of a DNA template; occurs in the nucleolus; also know as RNA synthesis
Process of  building a protein polypeptide using the code on an mRNA; the small subunit of the ribosome binds to mRNA, allowing this process to occur; occurs at the ribosomes
Translation; occurs 20 amino acids per second
What do these characteristics describe? 5 Carbon sugar is ribose 4 bases are adenine, uracil, cytosine, and guanine single stranded shorter than DNA molecule has covalent bonds (phosphodiester bonds) has 5' and 3' ends C1 holds the nitrogenous bas  
Enzyme used to build RNA polymers; must be present; bind to promoter (specific DNA sequence that is the starting point of a gene)after the gene is turned on
RNA polymerase
The direction of transcription is always
DOWNSTREAM (toward the 3' end of the RNA or 5' end of the template strand)
Single strand of RNA that carries the information for making a protein; "intermediate molecule"; intiated at 5' end
Each 3 nitrogenous bases on the mRNA
codon (ONLY on mRNA)
Amino acid that always initiates a polypeptide chain
Met (AUG)
Single strand of RNA that folds back on itself to form a specific shape; transfers amino acid to ribsomes; has the anti-codons
tRNA that has an amino acid binded to its 3' end
Amino-acyl tRNA
Made of proteins bound to rRNA (ribosomal RNA) no membrane; 40% protein and 60% rRNA; split into large subunits (has 3 tRNA biding sites---E,P, and A) and small subunit (has a small mRNA binding site)
Large subunit binding sites
A site (aminoacyl site) the aminoacyl tRNA delievering the next amino acid in the sequence binds at this location. P site stands for polypeptide. It holds polypeptide chain being builit. E site stands for exit. tRNAs that have given up their amino acids to the growing polypeptide chain exit the ribsome.
The anticodon that is complementary to the codon attaches with ________ bonds.