DNA & RNA (Chapter 8) Flashcards

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Questions and Answers

What describes DNA in terms of structure?

A tangled mass

A single strand

A flat molecule

A double helix (correct)

Who created the double helix model?

James Watson & Francis Crick

What are the four nitrogen bases of DNA?

Adenine, Guanine, Cytosine, Thymine

What does a nucleotide consist of?

A sugar, a phosphate group, and one of the 4 nitrogen bases Signup and view all the answers

How many strands does DNA have?

Two Signup and view all the answers

How many strands does RNA have?

One Signup and view all the answers

What nitrogen base replaces Thymine in RNA?

Uracil Signup and view all the answers

What base is Thymine paired with in DNA?

Adenine Signup and view all the answers

What base is Cytosine paired with in DNA?

Guanine Signup and view all the answers

What base is Adenine paired with in RNA?

Uracil Signup and view all the answers

What base is Guanine paired with in RNA?

Cytosine Signup and view all the answers

What sugar makes up DNA?

Deoxyribose Signup and view all the answers

What sugar makes up RNA?

Ribose Signup and view all the answers

What are nucleotides?

Monomers of DNA Signup and view all the answers

What does mRNA do?

Delivers the genetic code to ribosomes Signup and view all the answers

What is a gene?

A segment of DNA that codes for a particular protein Signup and view all the answers

Why is RNA necessary to act as a messenger?

Because DNA is too big to fit through the nuclear pores Signup and view all the answers

Why is DNA referred to as the 'blueprint of life'?

Because it controls every process in our body Signup and view all the answers

What are ribosomes?

Organelles that make proteins Signup and view all the answers

What is DNA replication?

Copying DNA Signup and view all the answers

What is DNA polymerase?

An enzyme that joins nucleotides while making DNA strands Signup and view all the answers

When does DNA copy itself?

Right before cell division Signup and view all the answers

What is transcription?

Copying DNA to make mRNA Signup and view all the answers

What is a codon?

Three mRNA bases in a row Signup and view all the answers

What does each codon code for?

An amino acid Signup and view all the answers

What amino acid does every strand of mRNA start with?

Methionine Signup and view all the answers

What amino acid does every strand of mRNA end with?

A 'stop' codon/signal Signup and view all the answers

What is a mutation?

A change in DNA Signup and view all the answers

What is translation?

Process in which mRNA is decoded and amino acids are joined together Signup and view all the answers

What is a polypeptide?

A chain of amino acids linked together by peptide bonds Signup and view all the answers

What is a protein?

A macromolecule made of amino acids Signup and view all the answers

What is DNA?

A double-stranded molecule that contains genetic information Signup and view all the answers

What is RNA?

A single-stranded nucleic acid that contains the genetic code Signup and view all the answers

What are the base pairing rules for DNA?

A-T & C-G Signup and view all the answers

What are complementary strands?

Strands that are the exact opposite of each other Signup and view all the answers

What is replication?

Copying a new strand of DNA from a parent strand Signup and view all the answers

What is a template strand (parent strand)?

The 'master copy' used to copy a new strand Signup and view all the answers

What is the central dogma?

DNA -> RNA -> Protein Signup and view all the answers

How many types of RNA are there?

Three (messenger RNA, transfer RNA, and ribosomal RNA) Signup and view all the answers

What is RNA polymerase?

An enzyme that bonds nucleotides together to make an RNA strand Signup and view all the answers

What is transfer RNA (tRNA)?

Transfers amino acids to a growing protein Signup and view all the answers

What does messenger RNA (mRNA) do?

Delivers the genetic instructions from DNA to ribosomes Signup and view all the answers

What is an anticodon?

Group of three bases on a tRNA molecule that pair with an mRNA codon Signup and view all the answers

What is a promoter?

A portion of the mRNA which attracts RNA polymerase to begin transcription Signup and view all the answers

What is an operon?

A group of prokaryotic genes that operate together Signup and view all the answers

What is an exon?

Sequences of DNA that are used in coding for proteins Signup and view all the answers

What is an intron?

DNA sequences that are not involved in coding for proteins Signup and view all the answers

What is a point mutation?

Mutation that affects a single nucleotide Signup and view all the answers

What is a frameshift mutation?

Mutation that shifts the "reading" frame of the genetic code Signup and view all the answers

What is a mutagen?

A substance that can change DNA and cause mutations Signup and view all the answers

What is the most dangerous type of mutation?

Frameshift mutation Signup and view all the answers

Are mutations more dangerous at the beginning or at the end of a strand of DNA?

At the beginning Signup and view all the answers

Where does transcription take place?

The nucleus Signup and view all the answers

Where does translation take place?

The cytoplasm (on a ribosome) Signup and view all the answers

Where is DNA found?

In the nucleus Signup and view all the answers

Where is RNA found?

In the nucleus, on ribosomes, and in the cytoplasm Signup and view all the answers

Study Notes

DNA Structure and Function

DNA is described as a double helix, resembling a twisted ladder.
Composed of four nitrogen bases: Adenine (A), Guanine (G), Cytosine (C), and Thymine (T).
DNA consists of two strands, while RNA has a single strand.
Nucleotides are the monomers of DNA, containing a sugar (deoxyribose), a phosphate group, and a nitrogen base.

Base Pairing

Thymine pairs with Adenine (A-T), and Cytosine pairs with Guanine (C-G) in DNA.
In RNA, Uracil replaces Thymine; thus, Adenine pairs with Uracil (A-U).
Codons consist of three mRNA bases in sequence, and each codon codes for a specific amino acid.

RNA and its Functions

mRNA (messenger RNA) conveys genetic information from DNA to ribosomes for protein synthesis.
tRNA (transfer RNA) brings amino acids to the growing polypeptide chain.
rRNA (ribosomal RNA) is a component of ribosomes, facilitating protein synthesis.

Transcription and Translation

Transcription occurs in the nucleus, converting DNA into mRNA.
Translation happens in the cytoplasm on ribosomes, decoding mRNA and forming polypeptides.
Every mRNA strand starts with Methionine and ends with a stop codon.

Gene and Proteins

A gene is a DNA segment that codes for a particular protein.
Proteins are macromolecules formed from amino acids linked into polypeptides.

DNA Replication

DNA replication occurs before cell division, ensuring that genetic information is passed on to daughter cells.
DNA polymerase is the enzyme facilitating nucleotide binding during replication.

Mutations

Mutations represent changes in DNA; they can be point mutations (affecting a single nucleotide) or frameshift mutations (shifting the reading frame by insertion/deletion).
Frameshift mutations are often more severe, potentially affecting multiple downstream codons.

Gene Regulation

Operons are groups of prokaryotic genes operating together.
Exons are important DNA sequences coding for proteins, while introns are non-coding sequences without known functions.

Genetic Code

The central dogma of molecular biology is DNA → RNA → Protein, involving replication, transcription, and translation.
RNA polymerase synthesizes RNA strands by bonding nucleotides together during transcription.

Cellular Locations

DNA resides in the nucleus, while RNA is found in the nucleus, ribosomes, and cytoplasm.
DNA's large size prevents it from exiting the nucleus directly; RNA serves as the messenger carrying code to ribosomes.

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Description

Test your knowledge on the fundamentals of DNA and RNA with these flashcards. This quiz covers key concepts such as the structure of DNA, the contributions of Watson and Crick, and the components of nucleotides. Perfect for reinforcing your understanding of molecular biology.