1010 Exam #2 Material

Cellular Reproduction: Overview

• Cellular Reproduction/Division

  • Production of new cells

  • Involves creating two daughter cells from a single parent cell.

Key Concepts

• Parent Cell Process

  • Replicates its cellular contents, especially DNA (nuclear, mitochondrial, chloroplast).

  • The cell contents move to opposite ends of the cell, leading to division.

• Types of Cell Division

  • Mitosis: produces genetically identical daughter cells.

  • Meiosis: produces genetically different daughter cells (gametes).

Purpose of Cell Division

• Mitosis Functions

  • Replaces damaged or dead cells.

  • Allows for growth, development, and maintenance of multicellular organisms.

  • Asexual reproduction: results in genetically identical offspring.

  • Examples: fragmentation, budding, binary fission, parthenogenesis.

• Meiosis Functions

  • Creates gametes essential for sexual reproduction.

  • Produces genetically unique offspring through fertilization.

  • Prevents doubling of chromosome number in offspring by creating haploid cells.

Eukaryotic DNA and Cell Division

• Chromosome Duplication Process

  • All chromosomes must be replicated before division.

  • Both strands of DNA form sister chromatids joined at a centromere.

  • Sister chromatids separate during cell division to ensure each daughter cell receives one chromatid.

The Cell Cycle

• Cell Cycle Phases

  • Comprised of Interphase (G1, S, G2) and Mitotic Phase.

  • Interphase: Normal cellular functions and preparation for division.

    • Doubles cellular contents (organelles, DNA).

    • Checks for errors before mitotic division.

  • Mitotic Phase:

    • Mitosis divides into four main stages: Prophase, Metaphase, Anaphase, Telophase.

    • Cytokinesis: Cytoplasm division creating two separate, identical cells.

Stages of Mitosis

• Prophase: Chromatin condenses, chromosomes become visible, nuclear envelope breaks down, spindle fibers form.

• Metaphase: Chromosomes align at the cell's equator, spindle fibers attach to centromeres.

• Anaphase: Sister chromatids are pulled apart towards opposite poles of the cell.

• Telophase: Two complete sets of DNA reach opposite sides, the nuclear envelope reforms, and cell begins to divide (cleavage furrow or cell plate forms).

Cancer and the Cell Cycle

• Cancer Characteristics

  • Cancer is termed the "disease of the cell cycle" due to uncontrolled division.

  • Cells may fail checkpoints due to gene mutations leading to genetic instability.

  • Results in tumors: benign (localized) or malignant (spread).

• Cancer Treatment Options

  • Surgery, Radiation Therapy, Chemotherapy, Hormone Therapy, Immunotherapy, Cryotherapy.

• Cancer Prevention Strategies

  • Avoid smoking, exercise, skin protection, balanced diet, regular check-ups, hereditary awareness.

Meiosis Overview

• Meiosis Function

  • Critical for sexual reproduction, provides genetic diversity among offspring.

  • Produces gametes with half the chromosome number (haploid) compared to somatic cells (diploid).

• Chromosome Ploidy

  • Humans have 46 chromosomes in somatic cells (22 pairs of autosomes + sex chromosomes).

  • Female: XX, Male: XY.

Meiosis Process

• Comparison with Mitosis

  • Both processes start with one round of chromosome duplication during interphase.

  • Mitosis: one cell division results in two identical diploid cells.

  • Meiosis: two rounds of division yield four genetically unique haploid cells.

Gene Variability in Meiosis

• Independent Assortment and Crossing Over

  • Happens during metaphase I and prophase I, respectively, contributing to genetic diversity.

  • Results in numerous genetic combinations in gametes.

• Nondisjunction: failure of chromosome separation during meiosis which can lead to aneuploidy.

Aneuploidy and Its Impact

• Aneuploidy: results from extra or missing chromosomes, more serious in autosomes than sex chromosomes.

  • Common Conditions: Down Syndrome (Trisomy 21), Klinefelter's Syndrome (XXY), Turner Syndrome (XO).

Genetic Principles and Inheritance Patterns

• Mendelian Genetics Basics

  • Heredity is the transmission of traits from one generation to the next.

  • Gregor Mendel laid the groundwork for genetic principles through pea plant studies.

• Punnett Squares: used to predict offspring genotypes and phenotypes from parents’ genetic makeup.

• Inheritance Patterns: are varied - can be dominant, recessive, incomplete dominance, or codominance.

Non-Mendelian Inheritance

• Complex Inheritance Patterns

  • Include incomplete dominance, codominance, and polygenic inheritance.

  • Pleiotropy represents single genes influencing multiple traits.

  • Epigenetics involves environmental influence on heredity.

Protein Synthesis and DNA Structure

• DNA Structure

  • Composed of nucleotides with a phosphate backbone and nitrogenous bases.

  • Base pairing is crucial for DNA replication and protein synthesis.

• Transcription and Translation

  • Process converting DNA sequences into proteins through RNA intermediates in the nucleus and cytoplasm.

• Mutations: changes in DNA sequences can be random or caused by external factors, leading to genetic diversity.