sem 2 final: part 2 Flashcards
What happens during G1 phase of INTERPHASE?
Gene expression and cellular respiration (producing ATP)
What happens during S phase of INTERPHASE?
DNA replicates creating two identical DNA strands
What happens during G2 phase of INTERPHASE?
Cell prepares to divide by replenishing energy, synthesizing proteins, and growing in size
What happens during the phases of MITOSIS (prophase, metaphase, anaphase, telophase)?
PROPHASE: Chromosomes condense forming two chromatids. Nuclear membrane disintegrates causing spindle to form. METAPHASE: Spindle organizes chromosomes on equator of the cell. Some spindle fibers attach to the centromeres and some span the cell. M-checkpoint occurs. ANAPHASE: Some spindle shorten which pull the chromatids apart. Some spindle lengthen which cause cell to elongate. TELOPHASE: Two new nuclei form.
How do plant cells divide?
Plant cells construct a new cell plate. The materials needed to do so are delivered by vesicles from Golgi.
How do animal cells divide?
A ring assembles in the middle of cell creating a cleavage furrow that moves inward (energy using process) to separate the two cells.
Cyclins
Cyclins control cell cycle progression by determining whether it will be fast or slow. Mutations in cyclin genes can lead to cancer. Cells cannot progress in cell cycle unless specific cyclins (D, E, A, B) reach a certain concentration.
What’s chromatin?
Substance in cell’s nucleus that’s composed of DNA and proteins
Helicase
Unzips DOUBLE HELIX by breaking HYDROGEN BONDS at ORIGIN OF REPLICATION forming REPLICATION BUBBLES. Within replication bubbles are replication forks that elongate DNA.
Gyrase
Unwinds the supercoil of DNA in a way that keeps DNA from breaking, relieving strain.
Primase
Adds RNA nucleotides (primer) to complementary base pairs.
DNA Polymerase III
Adds DNA nucleoside triphosphate to RNA primer sequence in 5’ to 3’ direction.
DNA Polymerase I
RNA primers are digested and replaced with DNA nucleotides.
Ligase
Joins okazaki fragments on lagging strand to form a single DNA strand.
DNA Replication Order
Gyrase, Helicase, Single Stranded Binding Proteins, Primase, DNA Polymerase III, DNA Polymerase I, Ligase
What nitrogenous bases do PURINES have and how many rings do they have?
A & G, 2 rings
What nitrogenous bases do PYRIMIDINES have and how many rings do they have?
T U & C, 1 ring
Transcription
INITIATION begins when double helix unwinds and RNA polymerase binds to DNA. ELONGATION is when nucleotides are added to mRNA in 3’ to 5’ region. TERMINATION is when mRNA synthesis is complete which begins disassembly.
Role of nucleosomes
Represses all transcription processes
Role of promoter
Controls whether RNA polymerase can access the gene
Role of silencer & enhancer
Silencer & Enhancers are non-coding DNA base sequence that regulate gene expression
Role of repressor
When repressor is added to operator, promoter stops binding with RNA polymerase
Free ribosomes
Synthesizes proteins in mitochondria, chloroplasts, cytoplasm, and nucleus
Bound ribosomes
Synthesizes proteins in ER, Golgi apparatus, lysosomes, plasma membrane, and ones that are to be exported out of cell
Translation
INITIATION begins when mRNA binds to small & large ribosomal subunits. ELONGATION is when aminoacyl-tRNA binds to A site. TERMINATION is when release factor binds to A site and disassembly begins.
Single Stranded Binding Proteins
Bind to parental DNA right after helicase to prevent 2 single strands from reforming double helix
