Richardson Honors Biology Unit 2 Review

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Questions and Answers

What role does the TATA box play in the transcription process?

It signals the termination of transcription.

It functions as a promoter for protein synthesis.

It prevents the binding of RNA polymerase to the DNA.

It indicates where RNA polymerase should bind to DNA. (correct)

Which statement about the transcription process is true?

Transcription occurs in the cytoplasm in eukaryotes.

RNA polymerase transcribes all strands of DNA.

Only the coding strand of DNA is transcribed.

The template strand of DNA is the one that is transcribed. (correct)

Which of the following statements accurately describes nucleotides?

They consist of a sugar, phosphate group, and a nitrogenous base. (correct)

They play no role in genetic information storage.

They are only found in RNA.

They are the building blocks of proteins.

What is one of the key functions of genetic material?

To act as a genetic code for all life. Signup and view all the answers

During transcription, what happens to the DNA double helix?

RNA polymerase opens the double helix to access the template strand. Signup and view all the answers

What role does RNA polymerase serve during DNA replication?

It starts a new chain by adding RNA nucleotides. Signup and view all the answers

What does the term 'semi-conservative' imply about DNA replication?

Each new double helix consists of one original and one newly synthesized strand. Signup and view all the answers

Which statement correctly describes the nitrogenous bases in nucleic acids?

Adenine and guanine are purines, while thymine and cytosine are pyrimidines. Signup and view all the answers

What distinguishes DNA from RNA?

RNA has uracil instead of thymine and is usually single-stranded. Signup and view all the answers

According to Chargaff’s rules, if adenine constitutes 22% of the DNA, what percentage of the DNA would be thymine?

22% Signup and view all the answers

Which of the following best defines the structure of purines and pyrimidines?

Purines have two ring structures, while pyrimidines only have one. Signup and view all the answers

Which type of RNA is primarily responsible for transferring amino acids during protein synthesis?

tRNA Signup and view all the answers

What function does ligase perform in DNA replication?

It connects various fragments of DNA together. Signup and view all the answers

What was the primary reason scientists initially considered protein as the genetic material instead of DNA?

Proteins have a greater diversity of structures due to more monomer units. Signup and view all the answers

Which of the following correctly names the chemical components that differentiate nucleic acids from proteins?

Nucleic acids contain phosphorous; proteins contain sulfur. Signup and view all the answers

Which bond forms between the phosphate group of one nucleotide and the sugar of another in a DNA strand?

Phosphodiester bond Signup and view all the answers

In the context of DNA structure, what does 'antiparallel' refer to?

The strands run parallel but in opposite directions. Signup and view all the answers

How many hydrogen bonds form between adenine and thymine in a DNA structure?

2 Signup and view all the answers

What role does DNA polymerase play during DNA replication?

It adds new DNA nucleotides in the 5' to 3' direction. Signup and view all the answers

What is the primary function of helicase during DNA replication?

It unzips the DNA by breaking hydrogen bonds between base pairs. Signup and view all the answers

Why is DNA described as a double helix?

It has two strands that twist together. Signup and view all the answers

Study Notes

Genetic Material and Historical Context

Scientists initially believed proteins were the genetic material due to 20 amino acids vs. 4 nucleotides in DNA.
Hershey and Chase demonstrated that DNA, not proteins, is the genetic material using viruses, which consist of a protective shell and genetic material.

Key Components of DNA

A DNA nucleotide consists of three parts: phosphate, 5-carbon sugar, and nitrogenous base.
The phosphate and sugar form the DNA backbone.
DNA nucleotides connect via phosphodiester bonds; the 5' end attaches to the growing chain, facilitated by DNA polymerase.

Base Pairing and Structure

Adenine pairs with thymine through 2 hydrogen bonds; cytosine pairs with guanine through 3 hydrogen bonds.
DNA is described as a double helix because it consists of two strands that twist together.
Strands run in opposite directions, termed antiparallel.

DNA Replication Process

DNA replication is semi-conservative: each new DNA molecule contains one original and one new strand.
Key proteins involved in DNA replication include:
- Helicase: Unzips DNA by breaking hydrogen bonds.
- DNA Polymerase: Adds new nucleotides in the 5’ to 3’ direction.
- Primase (RNA Polymerase): Starts a new chain using RNA nucleotides as a primer.
- Ligase: Connects Okazaki fragments on the lagging strand.

Nucleotide Types and Functions

Purines (Adenine and Guanine): Two-ring structures.
Pyrimidines (Thymine and Cytosine): One-ring structures.
Chargaff’s Rules dictate that adenine pairs with thymine and cytosine pairs with guanine.

RNA vs. DNA

DNA is double-stranded; RNA is typically single-stranded.
DNA contains deoxyribose; RNA contains ribose.
RNA substitutes uracil for thymine and serves various roles (mRNA, tRNA, rRNA), unlike the singular role of DNA.

Transcription Details

Not the entire chromosome is transcribed; only specific genes are copied into RNA.
The TATA box initiates transcription by guiding RNA polymerase to the right location.
The terminator sequence signals the end of transcription.
Transcription takes place in the nucleus of eukaryotic cells.

Scientific Contributions

James Watson and Francis Crick are credited with elucidating the double helix structure of DNA.
Genetic material must copy itself perfectly and serve as the genetic code for all living organisms.

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Description

Prepare for your upcoming test on nucleic acids with this review sheet. This quiz covers fundamental concepts including the historical experiments that distinguished DNA as the genetic material. Dive into the details of the Hershey and Chase experiment and understand the compositions of viruses.