Biology Chapter 14 Flashcards

Questions and Answers

A codon is a group of three bases that can specify more than one amino acid.

False

Which of the following statements about mutations is false?

Mutations can lead to beneficial changes in an organism.

All mutations are harmful.

A knock-out mutation results in a total absence of the mutated protein. (correct)

A knock-out mutation refers to the loss of a protein's function but not necessarily to its complete absence.

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

Deletion

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?

One addition and one deletion Signup and view all the answers

If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?

Two Signup and view all the answers

If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?

An addition mutation and a deletion mutation Signup and view all the answers

According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway (A→B→C)?

Two Signup and view all the answers

The flow of information in a cell proceeds in what sequence?

from DNA to RNA to protein Signup and view all the answers

A codon consists of bases and specifies which will be inserted into the polypeptide chain.

three...amino acid Signup and view all the answers

The corresponding codon for the mRNA transcribed from the DNA template strand 5' AGT 3' is?

3' UCA 5' Signup and view all the answers

A gene from an organism can theoretically be expressed by any other organism.

True Signup and view all the answers

The direction of synthesis of an RNA transcript is _____?

5' —> 3' Signup and view all the answers

In which direction does the RNA polymerase move?

3' → 5' along the template strand Signup and view all the answers

Where does RNA polymerase begin transcribing a gene into mRNA?

It starts after a certain nucleotide sequence called a promoter Signup and view all the answers

What is the function of RNA polymerase?

It unwinds the double helix and adds nucleotides to a growing strand of RNA. Signup and view all the answers

Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression?

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end Signup and view all the answers

Which of the following best describes the significance of the TATA box in eukaryotic promoters?

It is the recognition site for a specific transcription factor. Signup and view all the answers

During RNA processing a(n) _____ is added to the 5' end of the RNA.

modified guanine nucleotide Signup and view all the answers

During RNA processing a(n) _____ is added to the 3' end of the RNA.

a long string of adenine nucleotides Signup and view all the answers

Spliceosomes are composed of _____.

small RNAs and proteins Signup and view all the answers

The RNA segments joined to one another by spliceosomes are _____.

exons Signup and view all the answers

Study Notes

Codons and Mutations

A codon is a triplet of nucleotide bases that specifies a single amino acid.
Knock-out mutation causes a loss of protein function, not necessarily a complete absence of the protein.
A deletion mutation occurs when one base is lost from a DNA sequence, altering the original sequence.
A combination of one addition mutation and one deletion can restore the reading frame of a gene.

Protein Changes from Mutations

Inserting a base and deleting another can lead to changes in two amino acids in the protein produced.
Mutations may cause a protein to differ by one central amino acid if the change occurs in the same codon.

Gene Function and Expression

According to Beadle and Tatum's hypothesis, two genes are necessary for a simple metabolic pathway involving two enzymes.
The flow of genetic information in cells follows the sequence: DNA → RNA → Protein.
Genes are universally translatable across organisms due to the conservation of the genetic code.

Transcription and RNA Synthesis

RNA transcripts are synthesized in the 5' to 3' direction, with nucleotides being added to the 3' end.
RNA polymerase moves along the DNA template strand in the 3' to 5' direction.
Transcription begins at a promoter region, and in eukaryotes, this requires transcription factors for RNA polymerase binding.

RNA Processing

RNA polymerase unwinds DNA and synthesizes RNA strands during transcription.
Eukaryotic gene expression includes the addition of a poly-A tail to the 3' end of mRNA and a 5' cap composed of a modified guanine nucleotide.
The TATA box in eukaryotic promoters serves as a recognition site for specific transcription factors.

Splicing

Spliceosomes, consisting of small RNAs and proteins, facilitate the joining of RNA segments.
The segments that are retained and joined by spliceosomes are known as exons, which contain the expressed regions of the gene.

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Test your knowledge on key concepts from Biology Chapter 14 with these flashcards. This quiz covers fundamental topics such as codons and mutations, providing an excellent review tool for mastering the material.