49 terms

IB Biology HL Topic 7 2016

Nucleic Acids and Proteins
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Terms in this set (...)

DNA structure
antiparallel strands, 3'-5' linkages called phosphodiester bonds, and H bonding between purines and pyrimidines
Nucleosomes
consist of DNA wrapped around 8 histone proteins and are held together by another histone protein
Exons
sequences of bases that are transcribed and not spliced out and therefore translated
Introns
in eukaryotic cells, these are sequences of bases that are transcribed, but not translated
5'-3'
direction that DNA replication occurs in
RNA polymerase
catalyzes the splitting of DNA into 2 strands for transcription
tRNA activating enzyme
each tRNA molecule is recognized by this type of enzyme that binds a specific amino acid to the tRNA, using ATP for energy
Proteins and ribosomal RNA
these molecules form part of the structure of ribosomes
Number of subunits in a ribosome
2- the large and small subunit of a ribosome
APE
when reading right to left, these three sites are the number of binding sites for tRNA on the surface of a ribosome
mRNA
messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome
Translation
occurs in a 5' to 3' direction
Translation
consists of initiation, elongation, translocation, and termination
Polysome
group of ribosomes moving along the same mRNA as they simultaneously translate it
Free ribosomes
synthesize proteins for use primarily within the cell
bound ribosomes
synthesize proteins primarily for secretion or for lysosomes
Primary structure
the number and sequence of amino acids in a polypeptide
Secondary structure
regular repeating structures, including beta-pleated sheets and alpha-helices stabilized by H bonds between groups in the main chain of the polypeptide
Tertiary structure
the 3-D conformation of a polypeptide contains alpha helices and Beta Pleated Sheets
Quaternary structure
the linking together of 2 or more polypeptides to form a single protein
Fibrous proteins
have a long and narrow shape; insoluble in water
Globular proteins
have a rounded shape and are mostly soluble in water
Collagen
example of structural function of proteins; it strengthens bone, tendon, and skin
Hemoglobin
example of transport function of proteins; it binds to oxygen in the lungs and transports it to respiring tissues
Myosin
example of movement function of proteins; it causes contraction of muscle fibers and causes movement in animals
Immunoglobulin
example of defense function of proteins; acts as antibodies
polar amino acids
have hydrophilic R groups; on the surface of proteins makes them water soluble; create channels through which hydrophilic substances can diffuse; cause parts of membrane proteins to protrude from the membrane
non-polar amino acids
have hydrophobic R groups; in the center of water-soluble proteins stabilize their structure; cause proteins to remain embedded in membranes
Metabolic pathways
consist of chains and cycles of enzyme-catalyzed reactions
Induced-fit model
extension of the lock-and-key model; until the substrate binds, the active site does not fit the substrate precisely; as the substrate approaches the active site and binds to it, the shape of the active site changes and only then does it fit the substrate; the substrate induces the active site to change, weakening bonds in the substrate during the process and thus reducing the activation energy
Enzymes
lower the activation energy of the chemical reactions they catalyze because the chemical environment provided by the active site for the substrate causes changes within the substrate molecule, which weakens its bonds; the substrate is changed into a transition state and this is achieved during binding to the active site = less energy
competitive inhibition
is the situation when an inhibiting molecule that is structurally similar to the substrate molecule binds or blocks the active site, preventing substrate binding
non-competitive inhibition
an inhibitor binding to an enzyme, in a place that is not the active site, that causes a conformational change in its active site, resulting in a decrease in activity
DNA methylation
a process when DNA transcription factors are impeded or the chromatin binds so tightly around histones that genes cannot be transcribed
Frederick Griffith
Credited for giving the first indication that DNA was responsible for passing on information and not protein. He did this in the mouse experiments. Look at Section 210 of Biozone
Hershey and Chase
1952; these researchers studied T2 virus, bacteriophage, which infects bacteria cells (in this case, E. coli). Used radioactive Sulfur and Radioactive Phosphorous to determine if protein or DNA was being injected into bacteria. It was determined that Radioactive Phosphorus was becoming a part of the DNA, showing that DNA was the hereditary material
Know the processes of transcription and translation
Refer to Section 212-214 of Biozone
Initiation in Translation
mRNA is attached to the small subunit of the ribosome, begins by the appropriate tRNA-Methionine binding to the first codon which is AUG in the "A" site of the ribosome
Elongation in Translation
This phase involves tRNAs bringing amino acids to the mRNA ribosomal comlex in the order specified by the codons of the mRNA. Proteins called elongation factors assist in binding the tRNAs to the exposed mRNA codons at the A site. The initiator tRNA moves to the P site. The ribosomes catalyse the formation of peptide bonds between adjacent amino acids.
Translocation in Translation
Translocation happens during the elongation phase. Translocation involves the movement of tRNAs from one site of the mRNA to another.
Termination
One of three stop codons appears at the open A site. A release factor fills in the A site. It catalyzes the hydrolysis of the bond linking the tRNA in the P site with the polypeptide chain. This frees the polypeptide.
Santa Claus
Who was mommy kissing under the mistletoe last night?
Reindeer
Arctic deer with large antlers and the most famous one has a red nose
Menorah
In the Jewish faith, a candelabrum with a central stem bearing seven candles; it is the oldest symbol in Judaism.
Christmas Tree
An evergreen tree decorated at Christmas
Frosty
Famous snowman with a corn cob pipe and a button nose
Star of David
Symbol of Judaism
Mistletoe
an evergreen decoration used during the holidays for people to kiss under
Who was mommy kissing under the mistletoe last night?
Santa Claus

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