Test 2 Flashcards
Nucleic Acid Structure
Phosphate group
Sugar
Nitrogenous Base
DNA Structure
stable double helix
stands run antiparallel
strands joined by H-bonds between NB
nucleotide pairing follows rules of complementation based on hydrogen bonding
RNA
single-stranded
complementary to some region of DNA
several functional types
uracil
not typically stable
mRNA
carries blueprint for protein
tRNA
carry amino acids to ribosomes
no coding
rRNA
structural component of ribosome (permanently)
Heterochromatin
highly packaged/more condense
Euchromatin
less packaged/more condensed
Histone
most common condensing proteins
positive charge
Nucleosome and Solenoid
when repeated, structures increase packaging/condensing
Chromatin
Interior of a chromosome
Transcription
DNA –> RNA
Translation
RNA –> Protein
Codon
code for amino acid during translation
64 total
T or F: The code is redundant but not ambiguous
T
Start Codons (AUG)
where the reading should begin
met (methionine)
Stop Codons (UAA, UAG, UGA)
not recognized by tRNA
signal to terminate translation
RNA Polymerase
synthesizes RNA from DNA template during transcription
RNA will be identical to which strand? Coding or Template?
Identical to Coding
(uses template to make compliment)
Transcription: Initiation
RNA polymerase recognizes and binds to promoter (transcription factors)
unwinds DNA creating single-stranded template
Transcription: Elongation
RNA polymerase builds RNA that is the complement to the template strand of DNA
polymerizes 5’ to 3’
reading 3’ to 5’
Transcription: Termination
arrangements of nucleotides cause RNA polymerase to dissociate from DNA template
Post-Transcriptional Process
mRNA must be modified first to be transported to cytoplasm
5’ cap
poly-a tail
to protect the RNA since it is not stable
RNA Splicing
introns are removed and exons bind together
Alternative Splicing
the cell has the ability to make several different proteins from a single gene
accomplished by including or excluding different exons
Translation: Initiation
mRNA binds to ribosome binding site with start codon in p-site
Translation: Elongation
2nd charged tRNA enters A-site
peptide bond formation
repeat the number of codons in the mRNA ending at the stop codon
Translation: Termination
initiated when stop codon enters the A-site
release factors cleave the polypeptide from the last tRNA
Goal of Cell Cycle
produce two identically identical daughter cells when they are needed
Cell cycle control
cytoplasmic signals
density-dependent inhibition
anchorage dependence
Density-dependent inhibition
crowded cells stop dividing
Anchorage Dependence
cells must be attached to the appropriate surface to divide
knows not to divide in certain areas
Cancer cells
do not respond to body’s control mechanisms
loss of anchorage dependence and density-dependent inhibition
Malignant Tumors
invade surrounding tissues and can metastasis (loss of anchorage dependence)
Proto-oncogene
any gene involved in cell cycle control
Oncogene
defective version of proto-oncogene
Mitotic Cell Division Goal
create genetically identical daughter cells
Genome
full set of DNA an organism carries
Chromosomes
genome divided into smaller units of DNA
Gene
sequences of DNA bases that carry the information necessary to produce and RNA molecule or protein
Allele
many different versions of a gene may exist among individuals
Diploids
contain somatic cells that have two sets of each chromosome called homologous chromosomes
Somatic Cells
normal body cells (not gametes, sperm, or egg)
Homologous Chromosomes
pair of chromosomes in a diploid organism
same length
centromeres in same location
same gene in same place
different alleles could be the difference (A –> a)
Haploid
one copy of every chromosome
Sister Chromatids
each replicated chromosome consists of 2 which separate during cell division
Mitosis: Interphase
s phase when DNA replicates
cell growth/normal cell life
G1, S, G2 phase
Mitotic Phase
division of nucleus
Mitosis: Prophase
chromosomes condense
mitotic spindle forms
centrosomes separate
Mitosis: Pre-metaphase
nuclear envelope/membrane fragments
kinetochore forms
microtubules extend from centrosome to kinetochore
mitotic spindle connects to kinetochore which attaches to centromeres
Mitosis: Metaphase
centrosomes reach opposite ends of cell
Chromosomes align in the middle (end to end)
Kinetochores of sister chromatids attached to microtubules from opposite sides
Mitosis: Anaphase
Sister chromatids separate
microtubules shorten pulling chromosomes towards centrosomes (opposite sides)
Mitosis: Telophase/Cytokinesis
Nuclear envelopes reform
chromosomes condense
division of cytoplasm
cell divides into 2
Non-kinetochore Microtubules
push against each other to elongate the cell
Goal of Meiosis
reduce the number of chromosome sets from diploid to haploid
have 4 daughter cells, each with a unique set of chromosomes
Meiosis: Interphase I
chromosome replicate: diploid cells with sister chromatids
Meiosis: Prophase I
Chromosomes condense and move around
nuclear envelope dissolves
spindles form
synapsis of homologous chromosomes
crossing over can occur between homologues too
Meiosis: Metaphase I
tetrads align at the metaphase plate
homologous chromosomes line up side by side relative to division poles and non-homologous chromosomes arrange end to end.
Meiosis: Anaphase 1
homologous pairs separate and move towards opposite ends of the cell
each homologous chromosome pair has a pair of sister chromatids
sister chromatids remain attached at centromere
Meiosis: Telophase/Cytokinesis I
Nuclear envelope reforms
2 haploid cells have been produced
Meiosis: Interphase II
no replication of chromosome
centrosomes and centrioles can duplicate here
Meiosis II
VERY similar to mitosis
Ploidy
set of homologues in a cell
Euploidy
entire haploid set of chromosomes gained or lost
Aneuploidy
general category of conditions where chromosome is gained or lost
Monosomy
loss of one chromosome
typically lethal
Turner Syndrome
Trisomy
addition of a single chromosome
mental retardation and or organ system failure
the larger the chromosome, the more lethal
