16 Questions
Which of the following statements about DNA replication is correct?
DNA replication results in two identical daughter DNA molecules.
What is the primary function of DNA replication?
To provide genetic material for new cells during cell division.
Which of the following enzymes is primarily responsible for DNA replication?
DNA polymerase
In which cellular structure does DNA replication occur in eukaryotic cells?
Nucleus
What is the process of DNA replication initiated by?
The formation of a replication fork
Which of the following statements about DNA replication is true?
DNA replication occurs in both prokaryotic and eukaryotic cells.
What is the role of histones in the structure of DNA?
Histones allow packaging of extremely long DNA strands and regulate DNA activity.
What is the purpose of DNA replication during the cell cycle?
To ensure each daughter cell receives a complete and error-free copy of the genetic information.
Which enzyme is responsible for unwinding the DNA double helix during replication?
Helicase
What is the difference between the leading and lagging strands during DNA replication?
The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments.
What is the purpose of the $S$ phase during the cell cycle?
The cell replicates its DNA to ensure each daughter cell receives a complete copy.
What is the role of RNA during protein synthesis?
RNA carries the genetic instructions from the DNA to the ribosomes, where proteins are synthesized.
Which type of RNA is responsible for carrying the genetic instructions from the nucleus to the ribosomes?
Messenger RNA (mRNA)
What is the role of tRNA during protein synthesis?
tRNA carries the amino acids to the ribosome and binds to the complementary codon on the mRNA.
What is the purpose of the stop codon during translation?
The stop codon signals the ribosome to release the completed polypeptide chain.
What is the role of DNA polymerase during DNA replication?
DNA polymerase adds new nucleotides to the growing DNA strands, synthesizing the new complementary strands.
Study Notes
Cellular Organelles
- Mitochondria:
- Function: ATP production
- Have their own DNA and manufacture their own ribosomes
- Located in the mitochondrial matrix between the cristae
- Lysosomes:
- Function: digestion and denaturation of biological macromolecules
- Allow calcium release from bones
- Peroxisomes:
- Function: degradation of harmful substances, neutralizing oxygen free radicals
- Contain enzymes to convert hydrogen peroxide (H2O2) to water and oxygen
The Endomembrane System
- Comprises: nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vesicles, and plasma membrane
- Functions: production, storage, and export of molecules, and degradation of harmful substances
Nucleic Acids
- DNA (Deoxyribonucleic Acid):
- Double-stranded helical molecule in the cell nucleus
- Provides instructions for protein synthesis
- Replicates before cell division to ensure genetic continuity
- RNA (Ribonucleic Acid):
- Single-stranded molecule
- Carries instructions for protein synthesis from DNA to ribosomes
- Types: mRNA, tRNA, rRNA
Chromatin and Chromosomes
- Chromatin:
- 30% DNA, 60% histone proteins, and 10% RNA chains
- Histones package and regulate DNA, shut down DNA when needed, and activate DNA segments for protein production
- Chromosomes:
- Formed from chromatin during cell division
- Each chromosome has a p-arm and q-arm, hinged at the centromere
Cell Division
- Meiosis:
- Halves chromosome number in daughter cells (gametes)
- Combines genetic information from parents during sexual reproduction
- Mitosis:
- Duplicates chromosomes, with one set given to each new daughter cell
- Occurs in response to growth, injury, and aging
The Cell Cycle
- Consists of: Interphase and Cell Division
- Interphase:
- Grows and prepares for cell division
- DNA replication occurs in the S phase
- Cell Division:
- Mitosis and cytokinesis
Transcription and Translation
- Transcription:
- Process of converting DNA code to RNA
- Occurs in the nucleus
- Translation:
- Process of converting RNA code to amino acid sequence
- Occurs in the cytoplasm
Proteins
- Composed of long, folded chains of amino acids
- Determine protein structure and function
- Genetic code determines protein production
Plasma Membrane and Cytosol
- Plasma membrane:
- Phospholipid bilayer structure
- Semi-permeable, allowing selective passage of molecules
- Cytosol:
- Fluid part of the cytoplasm
- Site of many metabolic reactions
Test your knowledge on cell organelles and their functions including mitochondria, lysosomes, and peroxisomes. Learn about their structures and roles within the cell.
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