Chapter 25 DNA
暂无描述。系统推荐的高质量记忆内容，适合每天坚持背诵学习。
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DNA is the “_____” for all proteins
Written instructions
These “written instructions” include:
• Letters (bases) • Words (codons) • Sentences (gene) • Punctuation (promoters, stop codons)
Who built a double helix model to demonstrate the concept of DNA?
James WATSON and Francis CRICK
mRNA
Messenger RNA -takes message from DNA to the ribosomes
rRNA
Ribosomal RNA Translates the information in mRNA.
tRNA
Transfer RNA Carry amino acids to the ribosomes to make proteins
Gene
a segment of DNA that specifies the amino acid sequence of a protein (or RNA)
Gene Expression
Making a protein from the gene
What are the stems in protein synthesis? (multi-step process…4 steps)
• DNA (master building plans) • mRNA (blueprints) • rRNA (construction site) • tRNA (construction worker)
What 2 steps are required in gene expression?
• Transcription 2. Translation
Transcription (gene expression)
• making a readable copy of gene from DNA • “transcribe” = to make a written copy • happens inside the nucleus
Translation (gene expression)
• Using the gene’s instructions to construction protein • “translate” = to turn from one language to another • happens at ribosome on E.R. or in cytoplasm
Gene Mutation
A change in the sequence of bases within a gene
Gene mutations can lead to ____ ____ in cells
Malfunctioning protein
What causes mutations? (3 causes)
• Errors in replication - DNA polymerase “proofreads” new strands, error rare • Mutagens - Radiation, UV light, chemicals - Rate is low, DNA repair enzymes monitor and repair • Transposons - “jumping genes” - can move to new locations and disrupt sequences
Who discovered the transposon, “jumping genes”?
Barbara McClintock
Which one of the following was NOT one of the discoverers of DNA? • Francis Crick • Maurice Wilkins • James Watson • Barbara McClintock • Rosealind Franklin
Barbara McClintock
Which one of the following is NOT one of the 4 bases in DNA? • Adenine (A) • Cytosine (C) • Guanine (G) • Thymine (T) • Uracil (U)
Uracil (U)
______ is making a mRNA copy of DNA? • Transcription • Translation • Transfer • Transduction
Transcription think, copy = transcribe
____ are composed of 3 bases and code for a specific amino acid • Nucleotides • Codons • Exons • Introns
Codons
Which type of RNA carries amino acids to the ribosome? • cRNA • mRNA • rRNA • tRNA
tRNA
Which type of mutation moves all of the nucleotides after the mutation?
Frameshift
According to the textbook, approximately when did the first cell evolve? • 4.6 Billion years • 3.5 Billion years • 2.1 Million years
3.5 Billion Years