bio 3 exam exam

DNA Biotechnology and Forensic Science

• Definition: Forensic science that integrates biology and mathematics.

Structure of DNA

• The nucleus of a cell contains most of its DNA, which is stored in chromosomes.
• The nucleus is surrounded by a double membrane known as the nuclear envelope.
• The DNA within the nucleus directs cellular activities.

DNA Characteristics

• The structure of DNA can be visualized as a ladder:
    - Phosphate and sugar form the sides of the ladder.
• Key components of nucleotides:
    - Nucleotide composition: Base + Phosphate + Sugar.
    - Bases include Adenine (A), Guanine (G), Thymine (T), and Cytosine (C).
• Base Pairing:
    - A pairs with T (two hydrogen bonds).
    - G pairs with C (three hydrogen bonds).

Chromosomal Structure

• DNA molecules are tightly coiled around proteins to form fibers called chromatins.
• Long chromatin fibers twist and fold to form chromosomes.
• Humans inherit DNA through chromosomes, which carry genetic information.

DNA Replication

• Definition: The process of splitting two DNA strands and combining them, one old strand and one new strand.
• Steps involved in DNA replication:
    1. DNA unwinds.
    2. Complementary bases pair up.
    3. DNA polymerase synthesizes the new strand.

Mutations

• Definition: A change in the nucleotide sequence of DNA, which can involve:
    - Replacing, deleting, or adding nucleotide bases.
• Effects of mutations can vary widely and are the raw materials of evolution through natural selection.

Transcription and Protein Production

• Transcription Process:
    - DNA is transcribed into messenger RNA (mRNA).
    - mRNA carries genetic information required for protein synthesis.

Cancer

• Cancer relates to cell structure and the function of different cell types.
• Example cell types:
    - Muscle cells (long fibrous shape, function: contraction).
    - Neurons (long axonal extensions, function: transmit signals).
    - Red blood cells (round, lack a nucleus, function: carry oxygen).
• Central idea: Structure determines function.

Major Cell Regions

1. Nucleus: Contains DNA.
2. Cytoplasm: The fluid medium for biochemical reactions.
3. Plasma Membrane: Regulates entry and exit of substances.

Organelles and Their Functions

• Ribosomes: Sites of protein synthesis.
• Rough Endoplasmic Reticulum (Rough ER): Responsible for folding and transporting proteins.
• Smooth Endoplasmic Reticulum (Smooth ER): Involved in lipid synthesis and detoxification processes.
• Golgi Apparatus: Modifies and ships proteins.
• Mitochondria: Powerhouses of the cell, producing ATP (energy).
• Vesicles: Transport materials within the cell.
• Lysosomes: Responsible for digestion of cellular waste.

DNA Storage

• DNA is stored in the form of chromatin (a loose structure) and condenses into chromosomes during cell division.

Structure of DNA

• Form: Double helix made of nucleotides composed of:
    - Sugar
    - Phosphate
    - Base (A, T, C, G)

Comparison: DNA vs RNA

DNA Replication (Semi-Conservative)

• Mechanism: Each newly formed DNA molecule consists of one old strand and one new strand.
• Steps involved in the replication process:
    1. DNA unwinds.
    2. Base pairing occurs.
    3. DNA polymerase synthesizes the new strand.
• Errors during replication lead to mutations which can be classified as:
    - Substitution
    - Insertion
    - Deletion
• Effects of mutations can be harmful, beneficial, or neutral.

DNA Profiling

• Method: Utilizes Short Tandem Repeats (STRs), which are unique patterns in each individual.
• Applications of DNA profiling include:
    - Crime investigation
    - Paternity testing.

Central Dogma of Molecular Biology

• Flow of information: DNA → RNA → Protein.
• Process implications:
    - DNA holds genetic information.
    - RNA transfers this information.
    - Proteins execute cellular functions.

Protein Synthesis Components

• Nucleus: Site for transcription of DNA to mRNA.
• Ribosomes: Site where translation occurs, converting mRNA into protein.
• tRNA: Transports amino acids to ribosomes during translation.

Polymerase Chain Reaction (PCR) vs DNA Replication

Early Discoveries in Biotechnology

• Structure of DNA (discovered by Watson & Crick).
• Development of PCR (Kary Mullis).
• Advancements in DNA sequencing.
• Significance: These discoveries have paved the way for modern biotechnology.

Applications of Biotechnology

• PCR: Amplifies specific DNA sequences.
• DNA sequencing: Reads the genetic code.
• Genetic engineering: Involves modifying the DNA of organisms.

Applications of DNA Profiling

• Utilized in solving crimes.
• Important in identifying individuals.
• Useful for conducting paternity testing.

Biotechnology Uses

• Law: In forensic science applications.
• Health: In gene therapy and medical research.
• Science: In various research disciplines.

Genetic Engineering

• Practices include:
    - Adding genes
    - Removing genes
    - Modifying existing genes
• Example: Creation of genetically modified crops (e.g., pest-resistant varieties).

Summary of DNA Flow

1. DNA (gene)
2. Transcription into mRNA
3. Translation into protein

Comparison of Transcription and Translation

Cell Structure Comparison

Common Features of Plant and Animal Cells

• Both share structures characteristic of eukaryotic cells:
    - Nucleus (houses DNA).
    - Mitochondria (energy production).
    - Ribosomes (protein synthesis).
    - Cell membrane (regulates external interactions).

Unique Structures in Plant Cells

• Cell wall: Provides rigid support.
• Chloroplasts: Sites for photosynthesis.
• Large central vacuole: Used for storage and maintaining pressure.

Unique Structures in Animal Cells

• No cell walls or chloroplasts.
• More flexible shapes allow for diverse functions.

Key Takeaways

• All eukaryotic cells share a fundamental design while specializing based on their functions.
• The nucleus functions as the control center for the storage and regulation of genetic information.