Chapter 4 Flashcards
DNA stands for
deoxyribonucleic acid
DNA components
sugar: deoxyribose
phosphate group
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 ______
phosphate;deoxyribose
what are the nitrogenous bases united by?
hydrogen bonds
genetic instructions for synthesis of proteins
genes
fine filamentous DNA material complexed with proteins
chromatin
histones (2)
- disk shaped clusters of proteins
- what DNA molecules wind around
histones are divided into ______
nucleosomes
2 parallel filaments of identical DNA
sister chromatids
what joins two chromatids together
centromere
RNA vs DNA (4)
RNA: 1 nucleotide; DNA: 2 nucleotides
RNA: ribose DNA:deoxyribose
RNA:uracil instead of thymine
RNA: smaller
3 types of RNA
mRNA
tRNA
rRNA
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
start codon
AUG
a sequence of 3 nucleotides that stands for one amino acid
base triplet
T/F all body cells contain identical genes, except sex cells & immune cells
TRUE
when a gene is activated what is made?
mRNA
in transcription DNA codes for____; while mRNA codes for protein during ______
mRNA; translation
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
chaperones
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?
hormones
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?
RNA primer
when do mutations occur?reasons?
-due to replication errors of environmental factors (viruses, chemical, & radiation)
interphase includes:
G1, S,G2 phases
mitosis phases?
prophase, metaphase, anaphase, telophase
G0 phase
determined at G1 checkpoint; where the cell leaves the cell cycle and cease dividing
the location of a particular gene on a chromosome
locus
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
allele
codominant
both alleles are equally dominant
ex. P1 (striped) P2 (pink)= offspring (striped & pink)
incomplete dominance
phenotype intermediate between traits each allele would have produced
ex. P1 (black) P2 (white)= offspring (gray)
one gene produces multiple phenotypes
pleiotropy
benign tumor (4)
- easier to treat
- slow growth
- contained in capsule
- WILL NOT metasize
malignant tumor (4)
- CANCER
- fast growth
- not enclosed
- WILL metasize
environmental cancer causing agents
carcinogens
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?
tumor-suppressor genes
