Genetics - Chapter 23

In an isoelectric focusing gel, proteins migrate until they reach the pH where their net charge is ______ . This gel is then placed on top of an SDS gel, which separates proteins according to their ______ .

0 ; size (or mass)

Arrange the steps of two-dimensional gel electrophoresis in order. Start with the earliest on top.

1. A sample of cell is lysed. 2. Protein extracted is loaded onto an isoelectric focusing gel 3. Proteins are separated by charge 4. Gel containing separated proteins is loaded onto a polyacrylamide gel that contains SDS 5. Proteins are separated by size 6. Separated proteins are stained with a dye

The human genome has about ______ genes.

22,000

How can bioinformatics be used to identify the function of a new gene?

By finding a homologous gene whose mechanism of activity is known

Which of the following is used in the search-by-content approach for identifying genes?

Codon bias

Which of the following can be designed to take a DNA sequence and translate it into an amino acid sequence?

Computer program

In BLAST program analyses, the relationship between the query sequence and each matching sequence is given what value?

E-value

Which of the following statements about the human genome is true?

It has approximately 22,000 genes, but only a subset of those genes are expressed in any given cell.

A region of a nucleotide sequence that does not contain any stop codons is called a(n)

Open Reading Frame

Which of the following processes account for the larger size of the proteome relative to the genome?

Posttranslational covalent modifications RNA editing Alternative splicing

Which of these methods is used to track the interactions and functions of proteins on a large scale?

Protein microarray

Which factors influence the amount of a specific protein that will be found in a cell?

Rate of mRNA translation Rate of degradation (turnover) of the protein Level of mRNA produced from the gene

In this figure, the letter S indicates the location of a stop codon. Which is the most likely reading frame and why?

Reading frame 3 because it has only one stop codon

Which of the following are used in the search-by-signal approach?

Stop codons Promoter sequence Start codons

Two-dimensional gel electrophoresis involves two different gel electrophoresis procedures. Which of the following statements about these procedures is true?

The first procedure utilizes a tube gel that separates based on charge, while the second employs a slab gel that separates based on molecular weight.

Which of the following statements about the genome and proteome is true?

The proteome of all species is usually much larger than the genome.

What is the goal of functional genomics?

To understand the roles of genetic sequences in a given species

Conserved sites within a polypeptide are more likely to be functionally important than non-conserved sites.

True

Alternative splicing is the process in which ______.

a single pre-mRNA is altered so that different proteins may be produced by the same gene

The proteome is typically much larger than the genome. This is due to three main phenomena: (1) _____ splicing; (2) RNA ______ ; and (3) _______ covalent modification.

alternative ; editing ; posttranslational

The mechanism by which different forms of mature mRNAs (messenger RNAs) are generated from the same pre-mRNA is called _______ ______ , which is also sometimes called exon shuffling.

alternative splicing

BLAST is a ______.

computer program that can locate homologous sequences within a large database

A site within a polypeptide that is identical across multiple species is called a _____ site

conserved

A large number of computer files that has been collected and stored in a single location is known as a(n)

database

Most genes ______.

encode proteins

The proteome refers to the ______.

entire collection of proteins made by a given organism

The field of ______ genomics aims to understand the roles of genetic (DNA, RNA, and amino acid) sequences in a given species.

functional

Gene families arise via ______.

gene duplications followed by sequence divergence

The process of identifying regions of genomic DNA that encode genes is called

gene prediction

Organisms that have a close evolutionary relationship tend to have ______.

genes with similar DNA sequences

Bioinformatics can help to identify the function of a newly determined gene by identifying a(n) _______ gene whose function is known.

homologous

Genes that are derived from the same ancestral gene are called

homologous genes

In a given species, the proteome is typically ______ the genome.

larger than

Posttranslational covalent modification is a phenomenon that ______.

leads to production of multiple functional proteins from the same DNA sequence

A computer program called BLAST can be used to identify homology between two DNA or protein sequences. BLAST stands for basic _______ ______ ______ tool.

local alignment search

The levels of a specific protein found in a cell depend on the amounts of _______ produced by transcription, the rate of mRNA _______ to synthesize the protein, and the ________ rate for the protein.

mRNA ; translation ; turnover

The molecular mass of a specific protein fragment can be measured by the technique of

mass spectrometry

Mass spectrometry is used to ______.

measure the mass of a peptide fragment

A protein _______ involves spotting hundreds of proteins onto a glass or silica slide.

microarray

Homologous genes in two different species that continue to serve the same function are called

orthologs

Gene ______ are produced by multiple gene duplications, which are followed by the accumulation of mutations.

paralogs ( or family)

This figure highlights an approach called _____ recognition.

pattern

An individual has two mutant copies of the gene that encodes the enzyme phenylalanine hydroxylase. This individual has the disease

phenylketonuria or PKU

The modification of a protein's structure after it has been synthesized is called ______ _______ modification.

posttranslational covalent

Gene prediction is the ______.

process of identifying regions of genomic DNA that encode genes

A computer _______ consists of a defined series of operations that can manipulate and analyze data in a desired way.

program

The majority of an organism's genes encode

proteins

A sequence of codons read in groups of three bases is known as a(n)

reading frame

Computer programs may identify a gene within a long DNA sequence using the _______ -by- _________ strategy. This approach looks for regions with nucleotide sequences that differ significantly from a random distribution.

search ; pattern

An approach that uses known sequences such as promoters, and start/stop codons to help predict whether a DNA sequence encodes a protein is called a(n) ______ - by- _______ strategy.

search ; signal

Two-dimensional gel electrophoresis can ______.

separate a mixture of proteins within a cell extract

The example shown in this figure is ______ recognition.

sequence

A reading frame is a(n) ______.

series of codons read in groups of three bases, beginning with the start codon

Homologous genes encode proteins that carry out ______.

similar functions

A DNA sequence can be translated in three forward reading frames. The correct reading frame for a protein-encoding gene is typically the one that is not interrupted by a(n) ______ codon.

stop

An open reading frame (ORF) is a stretch of nucleotides that does not contain any ______.

stop codons

The technique of ______ - _______ gel _______ is used to separate hundreds or even thousands of different proteins within a cell extract.

two dimensional electrophoresis