chapter 3 Flashcards
nucleic acids
DNA and RNA
nucleotides
the building blocks (monomers) of DNA and RNA
what makes up a nucleotide?
1 molecule of phosphoric acid, 1 sugar (deoxyribose/ribose), & a base
nitrogenous base
a purine hydrogen binds to a pyrimidine to create the rungs and the complimentary code
purines
adenine and guanine. heterocyclic aromatic compound with a pyrimidine ring fused with an imidazole ring
pyrimidines
thymine, uracil, and cytosine. heterocyclic aromatic compound with a pyrimidine ring with nitrogen atoms at the 1 + 3 positions
DNA basics
double stranded, antiparallel and connected by hydrogen bonds at the rungs
what does adenine bind to in DNA?
thymine
what does adenine bind to in RNA?
uracil
what does guanine bind to?
cytosine
what makes up a full helix?
10 pairs of nucleotides
RNA basics
single stranded, ribonucleic acid
gene expression
the process of transcribing and translating the genetic code of the DNA into proteins
how many chromosomes do humans have?
23 pairs
transcription
DNA to mRNA. occurs in the nucleus. DNA is unwound + separated into 2 strands by breaking the hydrogen bonds
RNA polymerase
privides energy to unwind and split the DNA chain and add a new RNA nucleotide to the growing chain
what is the responsibility of mRNA?
carries the complimentary code, formed during transcription, out of the nucleus to the endoplasmic reticulum
precursor mRNA
large immature, single stranded. gets chopped down (spliced). original RNA copy from DNA
small nuclear RNA (snRNA)
directs splicing of pre-mRNA. to form mRNA
messenger RNA (mRNA)
carries genetic code from nucleus to cytoplasm
transfer RNA (tRNA)
transports activated amino acids to ribosomes so they can be assembled into proteins
ribosomal RNA (rRNA)
joins with ribosomes in forming proteins. actually reads the mRNA and assembles the amino acids in the peptide chain
micro RNA (miRNA)
single strand RNA. 21-23 nucleotides regulate gene transcription + translation
translation
RNA to protein. occurs in cytoplasm near ER. mRNA carries start codon to initiate process. goes to rRNA which, with tRNA reads complementary sequencing in sets of 3
what does the amino acid order determine?
the secondary + tertiary 3D configuration of the protein
how are enzymes activated?
by other enzymes or signalers that typically end in -ogen
zygomens
the inactive/storage form of enzymes
what regulates intracellular functions?
the availability and activity of enzymes
what does the inactivation of the 1st enzyme inhibit?
chemical pathways
what happens when purines build up in the cells?
it will inhibit the production of other purines + promote the production of pyrimidines
gene expression allows us to…
adapt to our environment + allows each cell to perform its specialized function
what is the TATA box?
basal promoter for transcription, which is a sequence on DNA
why does cell reproduction need to be kept in check?
so that cells do not rapidly produce without causing cancer
what will decrease the reproduction rate of cells?
growth factors, available space, and collections of secretions from cells
telomeres
region of repetitive nucleotide sequences at the ends of chromatids that protect them from deteriorating
what cells are constantly reproducing?
bone marrow, germinal layers of the skin, + epithelium of the gut
how often do smooth cells reproduce?
once every few years
replication
the process by which 2 new complete sets of DNA are formed from an original template
mitosis
the actual process by which the cell splits into 2 new cells with equal chromosomes
prophase
condensation of DNA in the chromosomes. formation and migration of centromeres/centrosomes. mitotic spindle begins to form, with microtubule connections
prometaphase
fragmentation of the nuclear envelope. formation of aster spines
metaphase
chromosomes line up in the middle of the cell, while still connected to the centromere
anaphase
microtubules attached to each of the sister chromatids and pull them apart
telophase
chromosomes begin to unwind at their opposite ends of the cell and new nuclear membranes form around each clump of chromosomes. mitotic spindle disappears
how long before mitosis does DNA replication occur?
5-10 hours
how long does DNA replication take?
4-8 hours
what does DNA replication require?
enzymes (DNA polymerase + DNA ligase)
chromosome
a DNA double helix packed with histones (structural + regulatory proteins)
chromatid
1 DNA strand with surrounding histones
centromere
the area in the middle of a chromosome joining the 2 identical chromatids
aster
spiny star microtubules made by the centrioles
mitotic spindle/apparatus
all of the microtubule connections of the centrosomes to the chromatids and to each other
how long does mitosis last for?
30 minutes
cytokinesis
the actual division of the 2 daughter cells. uses actin and myosin to create a cleavage furrow that forms a constriction ring
how many chromosomes are present in anaphase?
92 total, 46 pairs
cell differentiation
changes in physical and functional properties of cells as they proliferate in the embryo to form different bodily structures + organs
apoptosis
programmed, orderly cell death
how does apoptosis occur?
proteolytic enzymes are made and released to break down old cells. phagocytic cells consume broken down cells
what causes gene mutations?
it is unknown because mutations are random
what mechanisms are in place to minimize gene mutations during replication?
after replication & before mitosis there are a few hours where proof-reading of the DNA occurs
