DNA: Replication and Central Dogma

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Questions and Answers

Which of the following describes hypertrophy?

Size of the female breast increases at puberty

Endometrial development in preparation for ovum implantation

Increased size of the uterus in pregnancy (correct)

Increase in liver size after partial hepatectomy

What is the term for the increase in the number of cells in a tissue?

Hypertrophy

Hyperplasia (correct)

Dysplasia

Metaplasia

Which example is associated with metaplasia?

Increased size of the female breast at puberty

Increased respiratory epithelium in vitamin A deficiency (correct)

Increased size of the uterus during pregnancy

Endometrial development in readiness for fertilization

Which of the following instances involves both hypertrophy and hyperplasia?

Increased size of the uterus in pregnancy Signup and view all the answers

Which condition is primarily characterized by the transformation of one cell type to another?

Metaplasia Signup and view all the answers

How many hydrogen bonds are formed between Cytosine and Guanine?

Three Signup and view all the answers

What is the nature of the DNA structure pertaining to its strands?

Antiparallel and complementary Signup and view all the answers

In the DNA sequence provided, what does the '5’' and '3’' indicate?

Directionality of the nitrogen bases Signup and view all the answers

What replaces the thymine nucleotides in the mRNA during transcription?

Uracil Signup and view all the answers

Which step is NOT part of the transcription process?

Translation Signup and view all the answers

What is formed in the transcription bubble during transcription?

An opened-up region of DNA Signup and view all the answers

What type of mutation alters a single nucleotide resulting in a premature stop codon?

Nonsense variant Signup and view all the answers

Which component makes up the sides of the DNA ladder?

Deoxyribose sugar and phosphate Signup and view all the answers

Which process describes the conversion of RNA into protein?

Translation Signup and view all the answers

What is the primary function of transcription in the gene expression process?

To copy DNA into mRNA Signup and view all the answers

What kind of mutation does not change the amino acid sequence of a protein?

Silent variant Signup and view all the answers

In DNA replication, what is the main role of the phosphodiester bond?

Linking sugar molecules in the backbone Signup and view all the answers

During transcription, what is the primary product synthesized from the DNA template?

RNA Signup and view all the answers

What structural difference distinguishes ribose from deoxyribose?

Ribose has an -OH group on the 2' carbon Signup and view all the answers

Which statement correctly describes hydrogen bonding in DNA?

Hydrogen bonds link hydrophobic bases inside the helix Signup and view all the answers

What is the main function of replication in genetic information flow?

To ensure genetic information is passed to offspring Signup and view all the answers

What are the possible outcomes if a mutation is identified but not repaired, and the cell does not undergo apoptosis?

A mutation will exist in the cell. Signup and view all the answers

Which type of mutation does not affect the activity of the protein it encodes?

Silent mutation Signup and view all the answers

What is a characteristic of a missense mutation?

It produces a change in one amino acid in the protein. Signup and view all the answers

What is the result of a nonsense mutation?

It creates a STOP codon in the mRNA transcript. Signup and view all the answers

What causes mutations to occur in the nucleotide/base sequence of DNA?

Random changes in the DNA during replication. Signup and view all the answers

What is the primary function of RNA interference (RNAi)?

To tag target mRNA for degradation. Signup and view all the answers

How many pairs of chromosomes does the human genome consist of?

23 pairs Signup and view all the answers

Which of the following describes homologous chromosomes?

Chromosomes of the same size and shape that carry the same type of genes. Signup and view all the answers

What defines a somatic cell?

All body cells except reproductive cells. Signup and view all the answers

What is the difference between diploid and haploid cells?

Diploid cells have two homologous chromosomes, whereas haploid cells have only one chromosome of each type. Signup and view all the answers

What is contained in a human genome?

Both genes and non-coding sequences. Signup and view all the answers

What is the role of the Human Genome Project?

To estimate the number of genes in the human genome. Signup and view all the answers

What term describes the observable characteristics of an organism?

Phenotype Signup and view all the answers

Study Notes

DNA: Replication and The Central Dogma

DNA is a double helix resembling a twisted ladder.
The sides of DNA are composed of alternating sugar and phosphate molecules.
The rungs of the ladder are pairs of four types of nitrogenous bases.
DNA is antiparallel: The two strands run in opposite directions.
Each strand of DNA is complementary to the other: The sequence of one strand can be determined from the other.
The Central Dogma explains the flow of genetic information in cells.
DNA replicates, resulting in copies of the original DNA sequence.
Genetic information is passed from DNA to DNA, preserving and transmitting information between generations.
DNA's information is expressed into proteins in two steps: transcription and translation.
Transcription: DNA transcribed into RNA (transcriptome).
Translation: RNA translated into Protein (proteome).

DNA Structure

Deoxyribose sugar in DNA is a single-ring pentose sugar with a hydroxyl (-OH) group on the 2' carbon.
The nitrogenous bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).
Adenine pairs with Thymine through two hydrogen bonds.
Cytosine pairs with Guanine through three hydrogen bonds.
Phosphodiester Bond: Covalent bond that links the 3’ carbon atom of one sugar molecule to the 5’ carbon atom of another.
The 3' end of DNA contains a free hydroxyl group, while the 5' end has a phosphate group.

RNA Structure

Ribose sugar in RNA is a single-ring pentose sugar with a hydroxyl (-OH) group on the 2' carbon.
The nitrogenous bases in RNA are adenine (A), uracil (U), guanine (G), and cytosine (C).
Uracil is only found in RNA and replaces thymine.
RNA is single-stranded and shorter than DNA.

Gene Expression and Transcription

Transcription: The process of copying a DNA sequence into mRNA.
The DNA double helix unwinds near the gene being transcribed, forming a transcription bubble.
Transcription occurs in three stages: initiation, elongation, and termination.
Transcription uses one of the two DNA strands as a template, creating an RNA sequence that is complementary to it.
The template strand is also called the non-coding strand.
RNA polymerase: The enzyme that synthesizes RNA using the template strand.
RNA polymerase binds to a promoter region on the DNA, signaling the start of transcription.
Transcription continues until RNA polymerase reaches a terminator sequence, signaling the end of transcription.
Post-transcriptional modification: The newly transcribed RNA molecule undergoes modifications, such as splicing and capping, before it can be translated into protein.

RNA Interference

RNA interference (RNAi): A process by which short RNA molecules interfere with gene expression.
Small interfering RNAs (siRNAs): Short RNA molecules that bind to complementary sequences in mRNA and tag it for degradation.

Human Genome

The human genome is the complete set of genetic material in a human cell.
It consists of approximately 3 billion DNA base pairs.
The human genome is organized into 23 pairs of chromosomes, for a total of 46 chromosomes.
Autosomal chromosomes: The 22 pairs of chromosomes that are not sex chromosomes.
Sex chromosomes: The pair of chromosomes that determine sex (XX for female, XY for male).
Homologous chromosomes: Pairs of chromosomes that contain the same genes, but with potentially different alleles.
Somatic cells: All body cells except reproductive cells.
Gametes: Reproductive cells (sperm and egg).
Diploid (2n): Having two sets of chromosomes (one from each parent).
Haploid (n): Having one set of chromosomes.
Genotype: The genetic makeup of an organism.
Phenotype: The observable characteristics of an organism.

Cell Cycle

Cell cycle: The series of events that a cell goes through from its formation to its division into two daughter cells.

Mutations

A mutation is a change in the nucleotide sequence of DNA.
Mutations can occur due to errors in DNA replication or damage caused by environmental factors.
Mutations can alter the amino acid sequence of protein, potentially affecting its function.
Mutations can be beneficial, harmful, or neutral.

Point Mutations

Point mutation: A change in a single nucleotide in a DNA sequence.
Silent mutation: A point mutation that does not change the amino acid sequence of the protein.
Missense mutation: A point mutation that changes the amino acid sequence of the protein.
Nonsense mutation: A point mutation that introduces a premature stop codon into the mRNA sequence, resulting in a truncated protein.

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Description

Explore the intricate structure of DNA and the processes of replication and the Central Dogma. This quiz covers the key concepts of how genetic information flows from DNA to RNA to proteins, as well as the relationship between DNA strands. Test your understanding of transcription and translation as fundamental steps in expressing genetic information.