Cell Structure and Function

• Robert Hooke was the first person to sketch and name cells.
• When a cell expands in diameter, volume increases by the cube of the diameter, and surface area increases by the square of the diameter.

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells do not have a true nucleus.
• Eukaryotic cells have a true nucleus.

Cell Component Functions

• Mitochondria: Produce ATP through cellular respiration.
• Endoplasmic Reticulum:
  • Rough ER: Involved in protein synthesis and modification.
  • Smooth ER: Involved in lipid synthesis and detoxification.

Cell Junctions

• Plasmodesmata are cell junctions not found in animal cells (they are found in plant cells).

Cytoskeleton Types

• Microfilaments
• Intermediate filaments
• Microtubules

Motor Proteins

• Motor proteins produce motion in the cell.
• Examples: Myosin, Kinesin, and Dynein.

DNA Structure

• DNA has a double helix structure.
• The backbone consists of alternating sugar and phosphate groups.
• Nitrogenous bases (Adenine, Thymine, Guanine, Cytosine) are attached to the sugar.

DNA Building Blocks

• Nucleotides are the building blocks of DNA.
• Each nucleotide consists of a deoxyribose sugar, a phosphate group, and a nitrogenous base.

Base Pairing in DNA

• Adenine (A) pairs with Thymine (T).
• Guanine (G) pairs with Cytosine (C).

DNA Replication

• DNA replication is the process of copying DNA.
• Enzymes involved:
  • Helicase: Unwinds the DNA double helix
  • DNA Polymerase: Synthesizes new DNA strands by adding nucleotides to the 3' end of a template strand.
  • Ligase: Joins DNA fragments.

Therapeutic Cloning

• Therapeutic cloning aims to create new, replacement tissues for nerves, heart, and muscles.

Human Karyotype

• A typical human karyotype has 22 pairs of autosomes and 1 pair of sex chromosomes, for a total of 23 pairs.

RNA vs. DNA

• RNA contains ribose sugar, while DNA contains deoxyribose sugar.
• RNA contains uracil (U) instead of thymine (T).
• RNA is typically single-stranded, while DNA is double-stranded.

RNA Classes

• Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes.
• Ribosomal RNA (rRNA): A structural component of ribosomes.
• Transfer RNA (tRNA): Carries amino acids to ribosomes during protein synthesis.

DNA and RNA Synthesis Enzymes

• DNA Polymerase: involved in DNA synthesis
• RNA Polymerase: involved in RNA synthesis.

Gene Definition

• A gene is a segment of DNA that specifies a sequence of amino acids in a polypeptide.

Translation Stages

• Initiation: mRNA binds to the ribosome, and the first tRNA brings the first amino acid.
• Elongation: tRNA molecules bring amino acids to the ribosome, and peptide bonds form between the amino acids.
• Termination: A stop codon is reached, and the polypeptide is released from the ribosome.

Codons and Anticodons

• Codons are sequences of three nucleotides in mRNA that specify particular amino acids.
• Anticodons are sequences of three nucleotides in tRNA that are complementary to mRNA codons.

The Genetic Code

• The genetic code contains 64 mRNA codons (triplets).

Stop Codons

• The triplets of stop codons are UAA, UAG, and UGA.

Amino Acids

• There are 20 amino acids in nature.

Mitosis vs. Meiosis

• Mitosis results in two identical daughter cells, while meiosis results in four genetically different daughter cells.
• Mitosis is involved in growth and repair, while meiosis is involved in sexual reproduction.
• Somatic cells undergo mitosis, while germ cells undergo meiosis.

Chromosome Number

• Somatic cells are diploid (2n).
• Gametes are haploid (n).

Mitosis Stages

• Prophase: Chromosomes condense, and the nuclear envelope breaks down.
• Metaphase: Chromosomes line up along the metaphase plate.
• Anaphase: Sister chromatids separate and move to opposite poles of the cell.
• Telophase: Chromosomes arrive at opposite poles, and the nuclear envelope reforms.

Cytokinesis

• Cytokinesis is cytoplasmic cell division.
• In animal cells, cytokinesis involves the formation of a cleavage furrow.
• In plant cells, cytokinesis involves the formation of a cell plate.

Tumors

• Benign tumors: Non-cancerous and do not spread to other parts of the body.
• Malignant tumors: Cancerous and can spread to other parts of the body (metastasis).

Common Features of Prokaryotic and Eukaryotic Cells

• Plasma membrane
• DNA
• Cytoplasm

Cloning

• Cloning an adult mammal does not have or bypasses meiosis, gamete formation, and fertilization.

Eukaryotic Cell Features

• Golgi bodies
• True nucleus
• Use organelles for compartmentalization
• A dynamic "skeleton" of proteins

Rough Endoplasmic Reticulum

• The rough endoplasmic reticulum is characterized by the presence of ribosomes throughout.

Cytoskeletal Elements

• Intermediate filaments
• Microfilaments
• Microtubules

Cell Junctions in Plant Cells

• Plasmodesmata are cell junctions found in plant cells.

Adenine Pairing

• In DNA structure, adenine only pairs with thymine.

Chromatin

• All DNA and its associated proteins in the nucleus is termed chromatin.

ATP Production

• Eukaryotic cells make most of their ATP in mitochondria.

DNA Building Block

• Uracil is a nucleotide which is not a DNA building block.

DNA Nucleotide

• A DNA nucleotide contains a nitrogen-containing base, a sugar, and a phosphate group.