13.1

Genes contain coded DNA instructions that tells cells how to build..?

proteins

Most genes contain instructions for assembling amino acids into..?

proteins

RNA then uses the base sequence copied from DNA to direct the production of..?

proteins

Proteins are assembled on ______________, small organelles composed of two subunits.

ribosomes

What is a triplet?

3 bases in DNA

These ribosome subunits are made up of several ribosomal RNA (rRNA) molecules and as many as __ different proteins.

80

What is a gene?

A segment of DNA that codes a protein.

What is a codon?

A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

Some pre-mRNA molecules may be cut and spliced in different ways in different tissues, making it possible for..?

A single gene to produce several different forms of RNA.

What is an anticodon?

An anticodon is the three unpaired bases on a tRNA that is complementary to one mRNA.

How does the cell make RNA?

In transcription, segments of DNA serve as templates to produce complementary RNA molecules.

__________ and _________ may also play a role in evolution, making it possible for very small changes in DNA sequences to have dramatic effects on how genes affect cellular function.

Introns, exons

The three main types of RNA are?

Messenger RNA (mRNA), Ribosomal RNA (rRNA), Transfer RNA (tRNA)

_________________ are signals in the DNA molecule that show RNA polymerase exactly where to begin making RNA.

Promoters

RNA has many functions, but most RNA molecules are involved in?

Proteins synthesis only

Biologists don't have a complete answer as to why cells use energy to make a large ________ molecule and then throw parts of that molecule away.

RNA

Similar signals in DNA cause transcription to stop when a new _______ molecule is completed.

RNA

The first step in decoding these genetic instructions is to copy part of the base sequence from DNA into..?

RNA

_______ molecules sometimes require bits and pieces to be cut out of them before they can go into action.

RNA

________, like DNA, is a nucleic acid that consists of a long chain of nucleotides.

RNA

Transcription requires an enzyme, known as _____ _______________, which is similar to DNA polymerase.

RNA polymerase

In prokaryotes, ______ ______________ and protein synthesis takes place in the cytoplasm.

RNA synthesis

RNA polymerase binds to _________________, regions of DNA that have specific base sequences.

promoters

What are the three important differences between RNA and DNA?

The sugar in RNA is ribose instead of deoxyribose, RNA is generally single-stranded not double-stranded, and RNA contains uracil in place of thymine.

How does RNA differ from DNA?

There are three important differences between RNA and DNA: (1) the sugar in RNA is ribose instead of deoxyribose, (2) RNA is generally single-stranded and not double-stranded, and (3) RNA contains uracil in place of thymine.

What are the products of transcription?

Transcripts (includes mRNA, tRNA, and rRNA)

RNA controls the assembly of _________ _________ into proteins. Each type of RNA molecule specializes in a different aspect of this job.

amino acids

The RNA molecules that carry copies of these instruction are known as ___________________ RNA (mRNA): They carry information from DNA to other parts of the cell.

messenger

You can think of an RNA molecule, as a _________________ copy of a segment of DNA, a working copy of a single gene.

disposable

The portions that are cut out and discarded are called..?

introns

The chemical differences make it easy for the ________________ in the cell to tell DNA and RNA apart.

enzymes

The remaining pieces, known as ___, are then spliced back together to form the final mRNA.

exons

When a protein is built, a transfer RNA (tRNA) molecule transfers each amino acid to the ribosome as it is specified by the coded messages in..?

mRNA

What happens following transcription?

mRNA leaves the nucleus through the nuclear pores and attaches to a ribosome where it will direct protein synthesis.

The cell uses DNA "______________" to prepare RNA "_______________".

master plan, blueprints

Each _________________ in both DNA and RNA is made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base.

nucleotide

RNA polymerase then uses one strand of DNA as a template from which to assemble ___________________ into a complementary strand of RNA.

nucleotides

In eukaryotes, introns are taken out of pre-mRNA molecules while they are still in the..?

nucleus

In eukaryotes, RNA is produced in the cell's ___________ and then moves to the ______________ to play a role in the production of proteins.

nucleus, cytoplasm

The DNA molecule stays safely in the cell's _______________, while RNA molecules go to the protein-building sites in the _______________-the ___________________.

nucleus, cytoplasm, ribosomes

The base sequence of the ________________ RNA complement the base sequences of the template DNA.

transcribed

RNA polymerase binds to DNA during ____________________ and separates the DNA strands.

transcription

Most of the work of making RNA takes place during ______________. During ____________________, segments of DNA serve as templates to produce complementary RNA molecules.

transcription, transcription