Core Principles of DNA, RNA, and Cell Biology

Deoxyribonucleic Acid (DNA)

Composition and Structure

• Name: Deoxyribonucleic Acid
• Composition: Deoxyribonucleotides (nucleotides with deoxyribose: Adenine (A), Guanine (G), Cytosine (C), Thymine (T))
• Structure: Outer skeleton with pentose and phosphate, bonded by complementary bases.

Location and Functions

• Location: In the nuclei of eukaryotic cells and the cytoplasm of prokaryotic cells.
• Functions: Controls cell activities and carries genetic information.

Ribonucleic Acid (RNA)

Composition and Structure

• Name: Ribonucleic Acid
• Composition: Ribonucleotides (nucleotides with ribose: Adenine (A), Guanine (G), Cytosine (C), Uracil (U))
• Structure: Single chain of ribonucleotides.

Location and Functions

• Location: In the nucleus and cytoplasm of cells.
• Functions: Protein synthesis.
  • mRNA (messenger RNA): Carries genetic material copied from DNA.
  • rRNA (ribosomal RNA): Makes up ribosomes.
  • tRNA (transfer RNA): Transfers amino acids to mRNA.

DNA Replication and Protein Synthesis

DNA Replication

• Process: An identical copy of each of the DNA strands is made.
• Semiconservative Replication: Two identical molecules are obtained, each made up of a new chain and an old one.
• Location: Takes place in the cell nucleus.
• Timing: Occurs in the S phase of interphase.

Translation (Protein Synthesis)

• Location: Takes place in the cytoplasm.

Cell Division and Chromosomes

Chromosomes

• Definition: Structures formed by the condensation of chromatin.
• Human Chromosomes: Humans have 46 chromosomes.
• During Cell Division: DNA forms chromosomes.
• Example: During cell division, a cell 2n=8 would present 16 chromatids.

Cell Cycle: Interphase

• Definition: Phase where the cell is not dividing.
• Duration: The longest phase of the cell cycle.
• Events: The centrioles duplicate during interphase.

Mitosis

• Number of Cells Formed: 2
• Number of Chromosomes of Daughter Cells: The same as the parent cell.
• Crossover: No
• Number of Divisions: 1
• Phases:
  • During Anaphase, each chromatid migrates to one pole.
  • During Telophase, the nucleolus and the nuclear membrane restore.

Meiosis

• Number of Cells Formed: 4
• Number of Chromosomes of Daughter Cells: Half of the chromosomes the parent cell has.
• Crossover: Yes
• Number of Divisions: 2

Key Cellular Structures and Organelles

Organelles and Their Functions

• Mitochondria: Organelle with a double membrane where cellular respiration takes place.
• Ribosomes: Formed by two subunits. These organelles are in all kinds of cells.
• Lysosomes: Perform cellular digestion.
• Centrioles: Organelles unique to animal cells; participate in the division of chromosomes in animal cells.
• Nucleolus: Where the components of the ribosomes are created.
• Nucleoplasm: Liquid in the nucleus.
• Rough Endoplasmic Reticulum (RER): Has ribosomes attached to the outer face of its membranes.
• Chloroplasts: Present in plant cells.

Cellular Structures

• Cell Wall: Algae, fungi, plant, and prokaryotic cells have a cell wall outside the plasma membrane.
• Cilia: Extensions of the plasma membrane.

Fundamental Cellular Processes

Photosynthesis

• Process: Transforms inorganic matter into organic matter.
• Organisms: Plants perform photosynthesis.

Cellular Respiration

• Organisms: Plants perform cellular respiration, and animal cells also perform cellular respiration.

Basic Genetics Terminology

Key Genetic Terms

• Phenotype: Observable characteristics (e.g., Dominant (D), dwarf (d)).
• Genotype: Genetic makeup (e.g., Homozygous (MM, mm), Heterozygous (Mm)).