DNA stands for
nitrogenous base: adenine
Purines vs Pyrimidines
purines: A & G (double ring)
pyrimidines: T & C (single ring)
each sidepiece is a backbone composed of ____ groups and ______
what are the nitrogenous bases united by?
genetic instructions for synthesis of proteins
fine filamentous DNA material complexed with proteins
- disk shaped clusters of proteins
- what DNA molecules wind around
histones are divided into ______
2 parallel filaments of identical DNA
what joins two chromatids together
RNA vs DNA (4)
RNA: 1 nucleotide; DNA: 2 nucleotides
RNA: ribose DNA:deoxyribose
RNA:uracil instead of thymine
3 types of RNA
what determines the nucleotide sequence in the DNA
the amino acid sequence
how many chromosomes do humans have?
46 chromosomes: 23 pairs
3 stop codons
UGA, UAG, UAA
a sequence of 3 nucleotides that stands for one amino acid
T/F all body cells contain identical genes, except sex cells & immune cells
when a gene is activated what is made?
in transcription DNA codes for____; while mRNA codes for protein during ______
enzyme that binds DNA and assembles mRNA. what signals this enzyme?
RNA polymerase; TATATA
exons are ____ while introns are ____
sense (spliced together); non sense
who are the 3 participants in translation?
mRNA, tRNA, rRNA
what binds mRNA?then what?
small sub-unit then the large sub-unit binds the small sub-unit
where does tRNA pick up the anticodon for translation?
from free amino acids in the cytosol
where are proteins headed for lysosomes or secretion made?
ribosomes or rough ER
is protein synthesis finished once the amino acid sequence is made? what has to happen?
no, the protein is functional only after it is coiled and folded into a precise secondary or tertiary structure
old proteins that help new proteins in folding into the proper shapes
what is an example that can determine if a gene is turned on or off?
how do cells synthesize other components for such as glycogen, fats, steroids, etc?
enzymes are proteins encoded by genes to synthesize this materials (indirect genetic control)
Steps for DNA replication (4)
- Double helix unwinds from histone
- Enzyme helicase opens one short segment at a time exposing its nitrogenous bases
- DNA polymerase move along each stand
- New histones are synthesized in cytoplasm
what is applied before DNA polymerase is attached?
when do mutations occur?reasons?
-due to replication errors of environmental factors (viruses, chemical, & radiation)
G1, S,G2 phases
prophase, metaphase, anaphase, telophase
determined at G1 checkpoint; where the cell leaves the cell cycle and cease dividing
the location of a particular gene on a chromosome
cells divide when (4):
- have enough cytoplasm for 2 daughter cells
- have replicated their DNA
- have adequate supply of nutrients
- stimulated by growth factor
cells do not divide when: (2)
- snugly contact neighboring cells
- nutrients or growth factors withdrawn
different forms of gene at the same locus on 2 homologous chromosomes
both alleles are equally dominant
ex. P1 (striped) P2 (pink)= offspring (striped & pink)
phenotype intermediate between traits each allele would have produced
ex. P1 (black) P2 (white)= offspring (gray)
one gene produces multiple phenotypes
benign tumor (4)
- easier to treat
- slow growth
- contained in capsule
- WILL NOT metasize
malignant tumor (4)
- fast growth
- not enclosed
- WILL metasize
environmental cancer causing agents
what percentage of cancers are hereditary
5% to 10%
what causes cell division to accelerate out of control?
oncogenes (positive feedback)
what can oppose the effects of oncogenes?