Cellular Respiration, Meiosis, Genetics, and Cell Structure

Posted on Nov 18, 2024 in Biology

Cellular Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O

Aerobic Respiration: A process of glucose degradation where oxygen is the final electron and proton acceptor. Glycolysis: C6H12O6 → 2 pyruvate. Pyruvate enters the mitochondria and is transformed, producing CO2, protons, and electrons. Electrons and protons move along the cristae until they reach O2, forming water. ATP is generated through this process.

Aerobic Respiration Equation: C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Meiosis

Meiosis is the process by which a cell reduces its chromosome number by half for sexual reproduction.

Phases:

  1. Meiosis I (Reduction Division): Reduces the number of chromosomes.
  2. Meiosis II: Similar to mitosis.

Meiosis I Phases:

Prophase I: Chromosomes duplicate. Each copy is called a chromatid. Homologous chromosome pairs align, twist, and exchange segments (crossing over). This genetic recombination makes us different from our ancestors.

Metaphase I: Homologous chromosome pairs align along the cell’s equator.

Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell, resulting in two haploid cells.

Telophase I: Chromosomes arrive at opposite poles, and the cell divides.

Meiosis II: Similar to mitosis, resulting in four haploid cells.

Chromatin

Chromatin is a substance composed of DNA, which consists of nucleotides. Each nucleotide is made up of three molecules: phosphoric acid, a sugar, and a purine or pyrimidine base.

The genetic code is formed by combinations of amino acids. There are 20 amino acids.

The karyotype is the complete set of chromosomes in a diploid state.

Mendelian Genetics

Mendel introduced terms like purebred, hybrid, parental generation, and filial generation.

  • Purebred: An organism with a specific trait that consistently produces offspring with the same trait.
  • Hybrid: Offspring of two individuals with different traits. The dominant trait is expressed in the hybrid (F1 generation), while the recessive trait is masked.

Mendel’s First Law:

Crossing a purebred yellow plant with a purebred green plant results in 100% yellow offspring. This demonstrates that the dominant trait (yellow) masks the recessive trait (green) in the F1 generation. Crossing two yellow F1 plants results in a 3:1 ratio of yellow to green offspring.

Prokaryotes

Prokaryotes are organisms without a nucleus, such as bacteria.

External Morphology:

Small size, various shapes (cocci, bacilli, and vibrios).

Internal Structure:

The cell wall has properties like antibiotic resistance. Lacks membrane-bound organelles but has areas for respiration, similar to mitochondria. Ribosomes synthesize proteins (70S ribosomes). DNA is single or double-stranded and can be associated with plasmids, which often carry antibiotic resistance genes.

Functions:

  • Nutrition: Autotrophic (photosynthetic or chemosynthetic) or heterotrophic.
  • Response to Environment: Require specific temperatures, though some can form resistant spores.

Fermentation

Glucose is converted to pyruvate through glycolysis, but instead of entering the mitochondria, it forms ATP and either alcohol or lactic acid.

Reproduction

  • Prokaryotes: Duplicate genetic material and divide into two.
  • Eukaryotes: Nucleus divides by mitosis (four stages).

Mitosis:

  • Prophase: Chromatin condenses into visible chromosomes. Centrioles migrate.
  • Metaphase: Chromosomes align along the cell’s equator. Spindle fibers attach to centromeres.
  • Anaphase: Sister chromatids separate and move to opposite poles.
  • Telophase: Chromosomes decondense. Nuclear membranes reform. The cell divides.

Eukaryotic Cell Structure

Three main parts: plasma membrane, cytoplasm, and nucleus.

  • Plasma Membrane: Outer boundary of the cell.
  • Cytoplasm: Viscous liquid containing organelles.
  • Nucleus: Contains genetic material.

Animal Cells:

  • Mitochondria: Produce energy.
  • Golgi Apparatus: Processes and packages proteins.
  • Centrioles: Involved in cell division.
  • Endoplasmic Reticulum: Synthesizes proteins and lipids.

Plant Cells:

  • Cytoskeleton: Provides structural support.
  • Vacuoles: Store water and other substances.
  • Lysosomes: Break down waste materials.
  • Chloroplasts: Perform photosynthesis.

Chromosomes and Karyotype


The main component of the nucleus are chromatin filaments are transformed into chromosomes during cell division. All are jagged in shape, size or y number. You all individuals of the same species have the same number of chromosomes.
Karyotype. Set of chromosomes in an individual. It is also the orderly disposition of these chromosomes by size oy form.
Human Karyotype
Human cells are diploid and its 44 chromosomes can be grouped in homologous pairs.
Male: 44 chromosomes are 22 pairs of homologous chromosomes, but the pair number 23 the two chromosomes are different from each other dl. One, X and Y.
Women: the chromosomes of each pair are homologous. the couple 23 the two X chromosomes are haploids: Cells that have 23 chromosomes, all different, they can not grouped.
Chromosomes, Genes and Characters
Chromosomes are the support of genetic information. The portion of chromosome that carries the information for a character called and all GENOME GEN.