DNA Unit Flashcards

Questions and Answers

Why are DNA strands called anti-parallel?

Because one strand is built in the 5' to 3' direction, and the other is in the 3' to 5' direction.

What is Chargaff's scientific contribution?

Chargaff's rule states that in any DNA strand, the percentage of A's and T's will be equal, and the percentage of G's and C's will be equal.

What was Franklin's scientific contribution?

She took the first photo of the double helix using x-ray crystallography.

What was Watson and Crick's scientific contribution?

They discovered the double helix shape. Signup and view all the answers

When is DNA replicated (doubled)?

In S Phase of the Cell Cycle. Signup and view all the answers

The central dogma of molecular biology is: DNA -> _____ -> Protein.

RNA Signup and view all the answers

Why is an mRNA copy of DNA necessary?

Because the directions for making proteins are contained in DNA, so the mRNA acts as a messenger of information to the ribosome. Signup and view all the answers

What is the finished product of DNA replication?

Two identical strands of DNA, each one with an original strand copy built by DNA Polymerase. Signup and view all the answers

What are the three major differences between RNA and DNA?

<ol> <li>RNA is single-stranded; DNA is double-stranded. 2. RNA has ribose sugar; DNA has deoxyribose sugar. 3. RNA contains uracil (U) in place of thymine (T).</li> </ol> Signup and view all the answers

If a DNA strand has the sequence ACATTACGG, what would the mRNA copy be?

UGUAAUGCC Signup and view all the answers

Where does transcription occur?

In the nucleus. Signup and view all the answers

Explain the three major steps of translation.

<ol> <li>mRNA leaves the nucleus and binds to a ribosome. 2. rRNA on the ribosome grabs the mRNA and begins reading it. 3. tRNA brings amino acids to the ribosome where they link to form proteins.</li> </ol> Signup and view all the answers

Where does translation occur?

At a ribosome in the cytoplasm. Signup and view all the answers

What is the structure of DNA?

DNA is a long molecule made of three basic parts: a sugar called deoxyribose, a phosphate group, and a nitrogen-containing base. Signup and view all the answers

What is the shape of DNA?

Double helix (twisted ladder). Signup and view all the answers

Who is Edwin Chargaff?

He noticed that the amount of guanine (G) equals cytosine (C) and adenine (A) equals thymine (T) in DNA. Signup and view all the answers

Who is Rosalind Franklin?

She developed the technique for X-Ray Crystallography to study DNA. Signup and view all the answers

Who are James Watson and Francis Crick?

They figured out the double helix structure of DNA and explained Chargaff's findings. Signup and view all the answers

What does DNA do?

DNA is the genetic code. Signup and view all the answers

What are the discontinuous pieces of DNA copied on the lagging strand called?

Okazaki fragments. Signup and view all the answers

What is messenger RNA (mRNA)?

mRNA carries information from DNA to ribosomes for protein production. Signup and view all the answers

What is transfer RNA (tRNA)?

tRNA helps transfer amino acids to the corresponding mRNA codons. Signup and view all the answers

What is ribosomal RNA (rRNA)?

rRNA is a major component of ribosomes and helps bond amino acids together to make proteins. Signup and view all the answers

What is transcription?

Transcription is the process of converting DNA to RNA in the nucleus. Signup and view all the answers

What is translation?

Translation is the process of converting mRNA to proteins at the ribosome. Signup and view all the answers

What is a nucleotide?

A nucleotide consists of a 5-carbon sugar called deoxyribose, a phosphate group, and nitrogenous bases in DNA. Signup and view all the answers

What is a gene?

Genes are coded DNA instructions that control the production of proteins within the cell. Signup and view all the answers

What is RNA Polymerase?

RNA Polymerase is an enzyme that adds RNA nucleotide bases to mRNA. Signup and view all the answers

What are codons?

Codons are groups of three nucleotides, each coding for one amino acid. Signup and view all the answers

Study Notes

DNA Structure and Function

DNA strands run in opposite directions, termed "anti-parallel" (5' to 3' and 3' to 5').
DNA is composed of three components: deoxyribose sugar, phosphate group, and nitrogenous bases.
The double helix structure resembles a twisted ladder, where base pairs form the rungs.

Key Scientific Contributions

Chargaff's rule: Equal percentages of A=T and G=C in DNA.
Rosalind Franklin: Developed X-ray crystallography technique, revealing the double helix structure.
Watson and Crick: Identified the double helix form and explained base pairing specifics.

DNA Replication and Cell Cycle

DNA replication occurs during the S phase of the cell cycle, producing two identical strands.
Discontinuous DNA segments on the lagging strand are known as Okazaki fragments.

Central Dogma of Molecular Biology

The central dogma outlines the flow of genetic information: DNA → RNA → Protein.
mRNA serves as a messenger, relaying instructions from DNA to ribosomes for protein synthesis.

RNA Types and Functions

Three main types of RNA:
- mRNA (messenger RNA) carries genetic information from the nucleus to ribosomes.
- tRNA (transfer RNA) transfers amino acids to the ribosome, aligning them according to mRNA codon sequences.
- rRNA (ribosomal RNA) forms ribosomes and aids in protein synthesis.

Transcription and Translation Processes

Transcription: The process of converting DNA into RNA occurs in the nucleus.
Translation: mRNA is translated into proteins at the ribosome; involves reading codons and linking amino acids.

Codons and Amino Acids

Codons are triplets of nucleotides that encode specific amino acids.
Each tRNA has a corresponding anticodon that pairs with mRNA during protein synthesis.

Additional Key Points

Genes are segments of DNA that contain instructions for producing proteins.
RNA polymerase: Enzyme responsible for synthesizing RNA from a DNA template.

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Description

Test your knowledge of DNA concepts with these flashcards. Explore key terms like anti-parallel strands and Chargaff's rule. Perfect for biology students looking to strengthen their understanding of genetic structures.