The genetic code

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Lecture 8

4 nucleotide bases, 20, triplet, codon

There are only ___ _____ ____ to specify ____ amino acids, so the genetic code is a ____ of nucleotides or ____.

degenarate, codon

The genetic code is _______ meaning most amino acids are specified by more than one ______.

accurate base-pairing, two, codon, tolerate, mismatch, third, glycine

Some tRNA molecules require _____ ___-_____ only at the first ____ positions of the ____ and can ____ a ___ at the _____ for example _____

initiates, methonine, terminates, nothing

The start codon ____ translation but also codes for ____. The stop codon ____ translation and codes for ____.

universal, simplest, most plants animals, firefly

Genetic code is ____ by most organisms from the ____ bacteria to the ____ complex ____ and _____. For example tobacco plant expresses a ______ gene.

Mutations, protein structure function, permanent, inheritable, DNA, spontaneously, low, random errors, external agents, damage DNA

______ are changes in one or a few nucleotides in a sequence that can affect ____ ____ and ______. It can cause _____, ______ alteration in the _____ sequence. It may arise _______, as a result of _____ frequency _____ _____ or may be induced by ____ ____ which ______ ______.

Point mutation, substitution, silent, missense, nonsense, insertion, deletion, frameshift

_____ ____ is a change in a single base pair. There are two types. 1. Nucleotide pair _____ which could be ____, _____ or _____. 2. Nucleotide pair ____ or _____ which could be _____.

replication, DNA polymerase, mutagenic agents, spontaneous chemical

Point mutations can arise from: mistakes in ______ by _____ _____, ______ _____ like UV light or _____ ____ reactions in cells.

no effect, A G U C

Silent nucleotide pair substitution has ____ ___ on amino acid sequence. Replaces ____ instead of ____ and ____ instead of _____.

changes, T C, A, G sickle-cell disease

Missense nucleotide pair substitution _____ an amino acid. _____ instead of _____ and _____ instead of ____. One example would be ____-____ ____.

stop codon, terminated prematurely, nonfunctional

Nonsense nucleotide pair substitution create a ______ ____. It causes translation to be _____ ______. Nearly all nonsense mutations lead to _____ proteins.

DNA repair mechanisms, excision repair

Most mutations are eliminated by ____ ____ ___ for example ___ ____ of DNA.

thymine, nuclease enzyme, two, damaged, DNA polymerase, missing nucleotides, DNA ligase, old

Excision repair: 1. A _____ dimer distorts the DNA molecule. 2. A ____ ____ cuts the damaged strand at ____ points and the ____ section is removed. 3. Repair synthesis by a _____ ____ fills in the ____ _____. 4. ____ ____ seals the free end of the new DNA to the ____ DNA making the strand complete.

response, changes, nutrients, gene expression, genetic information, totipotent, program, development, new embryo

Cells do not express all their genes. Prokaryote cell gene expression involves _____ to _____ in available ______. Eukaryote cell differentiation is regulated by _____ ____. Many specialized cells do not loose ____ _____. The nucleus is _____ which means it is able to _____ the _____ of a ____ ______.

egg cell ovary, nucleus, removed, fuse, grown, culture, implanted, uterus, embryonic development

Cloning a mammal: 1. take ____ ___ from _____. 2. the _____ is _____. 3. The cells are then _____. 4. the cells are ______ in _____. 5. They are then _____ in _____ of a 3rd organism. 6. Finally we have the ______ _____.

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