DNA and RNA Basics

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Questions and Answers

What distinguishes the building blocks of DNA from those of RNA concerning the sugar component?

RNA lacks a phosphate group, while DNA contains it.

DNA has a hydroxyl group on the 2' carbon, while RNA does not.

The sugar in DNA is ribonucleotide, while in RNA it is deoxyribonucleotide.

RNA has a hydroxyl group on the 2' carbon, while DNA does not. (correct)

What is formed during receptor-mediated endocytosis?

A membrane vesicle that engulfs the entire cell.

A channel that allows fluids to pass through the membrane.

A vesicle that transports cargo into the cell. (correct)

An external membrane that encloses extracellular fluid.

Which of the following is a correct statement regarding nucleotides?

Nucleotides are devoid of any phosphate group.

Nucleotides contain only a base and a sugar.

Nucleotides are joined by peptide bonds.

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

What type of molecule is dTMP, and why is it designated as such?

It is a deoxynucleotide because it contains thymine. Signup and view all the answers

What is the primary function of pinocytosis in cells?

To internalize extracellular fluid through membrane vesicles. Signup and view all the answers

What is the main principle of Mendel's Law of Segregation?

Alleles of a gene segregate during the formation of gametes. Signup and view all the answers

In a monohybrid cross involving two heterozygous parents, what is the expected ratio of dominant to recessive traits in the F2 generation?

3:1 Signup and view all the answers

What type of allele is responsible for free-hanging earlobes?

Dominant allele (E) Signup and view all the answers

Which trait is influenced by environmental factors in addition to genetic factors?

Tongue curling Signup and view all the answers

Why is red/green colorblindness more common in males than females?

It is located on the X chromosome. Signup and view all the answers

What is the inheritance pattern of freckles?

Dominant Signup and view all the answers

What is the probability of a child having attached earlobes if both parents are heterozygous for the earlobe trait?

25% Signup and view all the answers

Which of the following is true about PTC tasting?

One copy of the tasting allele is needed to taste PTC. Signup and view all the answers

What is the primary function of cyclins and cyclin-dependent kinases in the cell cycle?

To activate proteins for progression Signup and view all the answers

During which phase of the eukaryotic cell cycle does the chromosome double?

S Phase Signup and view all the answers

What is the main outcome of mitosis?

Formation of two genetically identical daughter cells Signup and view all the answers

What occurs during the prophase stage of mitosis?

Nuclear envelope disintegrates Signup and view all the answers

In meiosis, what is crossing over and why is it important?

It allows for the exchange of genetic material, increasing genetic diversity. Signup and view all the answers

Which structure is responsible for organizing and sorting chromosomes during cell division?

Mitotic spindle apparatus Signup and view all the answers

What happens during anaphase of mitosis?

Sister chromatids are separated and pulled to opposite poles. Signup and view all the answers

Which phase of the eukaryotic cell cycle involves intense protein synthesis in preparation for DNA synthesis?

G1 Phase Signup and view all the answers

What is the role of checkpoints in the cell cycle?

To ensure cells do not divide without proper conditions Signup and view all the answers

What is the term for the individual set of chromosomes in a cell?

Karyotype Signup and view all the answers

What aspect of eye color inheritance challenges the previous understanding of it being a simple recessive trait?

Eye color is influenced by the interaction of multiple genes. Signup and view all the answers

What is the primary purpose of a Punnett square in genetics?

To predict the probability of offspring genotypes and phenotypes. Signup and view all the answers

In a testcross to determine the genotype of an organism with a dominant phenotype, which individual is it crossed with?

An individual with a recessive phenotype. Signup and view all the answers

What does the notation in a pedigree analysis indicate when a square is filled in black?

The individual is an affected person with a dominant trait. Signup and view all the answers

Which of the following statements correctly describes Mendel's law of independent assortment?

The alleles of different genes are sorted into gametes independently. Signup and view all the answers

What type of inheritance causes hemophilia to be classified as sex-linked?

It is a recessive trait carried on the X chromosome. Signup and view all the answers

When referring to the human genome, how many genes are actively used to produce proteins?

About 19,900 genes. Signup and view all the answers

How many chromosomes do humans have in total?

46 chromosomes. Signup and view all the answers

What type of bond connects nucleotides in a nucleic acid?

Phosphodiester bond Signup and view all the answers

Which strand of DNA is synthesized continuously during replication?

Leading strand Signup and view all the answers

What is the role of DNA primase in DNA replication?

To synthesize RNA primers Signup and view all the answers

What type of replication occurs at the replication forks?

Bidirectional replication Signup and view all the answers

Which enzyme adds nucleotides in the 5' to 3' direction during DNA replication?

DNA polymerase III Signup and view all the answers

In the context of nucleotides, which component is attached to the 1' carbon of the sugar?

Nitrogenous base Signup and view all the answers

What mechanism ensures the accuracy of DNA replication?

Proofreading activity of DNA polymerase Signup and view all the answers

Which bond does DNA ligase create during DNA replication?

Phosphodiester bond Signup and view all the answers

What is the complementary strand for 5'-ATGC-3'?

3'-GCAT-5' Signup and view all the answers

What role does DNA topoisomerase play during DNA replication?

Relieves coiling ahead of the replication fork Signup and view all the answers

What type of DNA replication occurs in eukaryotes compared to bacteria?

Both eukaryotes and bacteria replicate bidirectionally Signup and view all the answers

Which of the following statements about the leading and lagging strands is true?

Lagging strand is synthesized along with RNA primers and DNA Signup and view all the answers

Study Notes

DNA Components

Each nucleotide consists of a sugar, phosphate group, and a nitrogenous base
Deoxyribose in DNA, Ribose in RNA
The nitrogenous base, adenine (A), thymine (T), cytosine (C), and guanine (G), are found in DNA
Uracil (U) replaces thymine in RNA
The phosphate group connects the 5' carbon of one deoxyribose to the 3' carbon of the next deoxyribose
The nitrogenous base is attached to the 1' carbon of the sugar

DNA vs. RNA

DNA uses the sugar deoxyribose, while RNA uses the sugar ribose
Deoxyribose is different from ribose because it lacks a hydroxyl (-OH) group at the 2'-carbon
DNA is typically double-stranded, while RNA is typically single-stranded

Nucleic Acid Structure

The nucleotides are linked together to form a polynucleotide chain
The phosphodiester bond connects polynucleotide chains
The phosphodiester bond is formed between the phosphate group of one nucleotide and the 3' hydroxyl group of the next
The phosphodiester bond forms the backbone of the DNA strand
The sequence of nucleotide bases determines the genetic information
The 5’ end has a free phosphate group, and the 3’ end has a free hydroxyl group
Nucleotide sequences are always written from the 5’ to 3’ direction

DNA Replication

DNA replication is the process by which DNA is copied
The two parental DNA strands separate, acting as templates for the synthesis of two new strands
DNA polymerase synthesizes the new strands by adding nucleotides to the 3' end of the growing strand
This is known as semiconservative replication
The AT/GC rule ensures that the newly synthesized strands are complementary to the original strands

Origin of Replication

The origin of replication initiates DNA replication
In eukaryotes, multiple origins of replication help to speed up the process
DNA polymerase can only extend the strand in the 5' to 3' direction.
This leads to a leading strand and a lagging strand

Leading Strand

Synthesized continuously in the 5' to 3' direction
RNA primase creates a primer for the polymerase to extend the strand
It only needs one primer to initiate DNA replication

Lagging Strand

Synthesized discontinuously in Okazaki fragments
Each fragment is primed with an RNA primer
RNA primers are removed and replaced with DNA nucleotides
DNA ligase joins adjacent fragments

Key Enzymes in DNA Replication

DNA helicase unwinds the parental strands to separate them.
DNA topoisomerase relieves strain on the DNA molecule ahead of the replication fork.
Single-strand binding proteins (SSBs) stabilize the separated strands and prevent them from re-annealing before replication.
DNA primase synthesizes short RNA primers to initiate DNA synthesis by DNA polymerase.
DNA polymerase III adds nucleotides to the 3' end of a growing DNA strand
DNA polymerase I removes RNA primers and replaces them with DNA nucleotides.
DNA ligase joins Okazaki fragments together.

DNA Polymerase Accuracy

DNA polymerase has a proofreading mechanism which removes mismatched nucleotides to ensure accurate DNA replication.
The base pairing between A-T and G-C provides stability to the correct pairing of nucleotides.

Understanding DNA & RNA

Knowledge of DNA structure and the process of replication is crucial for understanding heredity and genetic diseases.

Chromosome Structure

Chromatin is the complex of DNA and proteins found in the nucleus of eukaryotic cells
Heterochromatin is tightly packed chromatin, making it inaccessible for transcription.
Euchromatin is loosely packed chromatin, allowing access to transcription.
Centromere is critical for the proper segregation of chromosomes into daughter cells during cell division.
Chromatids are two identical copies of a chromosome.

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Description

This quiz covers the fundamental components of DNA and RNA, detailing the structure of nucleotides and the differences between the two nucleic acids. Understand the roles of deoxyribose and ribose, and explore the significance of phosphodiester bonds in nucleic acid formation.