Cell Cycle and Tissues - Exercises 7-10

• The lab exercise covers tissues and the cell cycle, corresponding to exercises 7-10.

Cell Cycle Learning Outcomes

• Describe the phases and structures of the cell cycle.
• Identify and sketch the stages of the cell cycle.
• Arrange models or drawings of cells in the correct sequence of their life cycle phases.

The Cell Cycle Overview

• The cell cycle refers to the series of changes a cell undergoes from its formation until it divides. A newly formed diploid cell (46 chromosomes) grows to a certain size before dividing.
• Division results in two new daughter cells, each with 46 chromosomes.
• Daughter cells replace the original cell, performing the same function.

Cell Cycle Phases

• Two main phases in the cell cycle are Interphase and M phase (aka mitosis).
• Interphase includes G1 phase for metabolism, S phase for DNA synthesis, and G2 phase for division preparation.
• Mitosis (PMAT) involves the division of the nucleus: prophase, metaphase, anaphase, and telophase.
• Cytokinesis is the final stage, involving the splitting of the cell's cytoplasm.
• The G0 state represents a mature cell that is not dividing with a variable time frame.

Mitosis (PMAT)

• Interphase is the time between cell divisions where DNA exists as thin chromatin threads inside the nucleus. DNA replication occurs during the S phase of interphase and organelles and centrioles duplicate.
• Prophase involves chromatin condensing into chromosomes, each with two chromatids joined at the centromere as centrioles move to opposite poles, the nucleolus disappears and microtubules form.
• Metaphase is when the chromosomes align in the center, associated with spindle fibers and some spindle fibers attach to the centromeres.
• Anaphase: chromatids separate, each becoming a chromosome, doubling the chromosome number; they move toward centrioles assisted by spindle fibers leading to cytokinesis.
• Telophase involves chromosomes unraveling, nuclear envelope formation, nucleoli forming, and cytokinesis completing to produce two cells.
• The end of mitosis leads to a new interphase, with two identical daughter cells formed.

Drawing and Labeling the Cell Cycle & Mitosis

• Draw a circle to represent the cell cycle and divide it into sections.
• Then label the sections: G1, G2, S, Mitotic (M) phase, Interphase, Prophase, Anaphase, Metaphase, Telophase, and Cytokinesis.
• Draw and label the stages of mitosis (Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis) as a class.

Tissues Overview

• Tissue: A layer or group of cells similar in size, shape, and function.
• Four types of tissues are: Epithelial, Connective, Muscle, and Nervous tissue.
• Epithelial tissue covers internal and external surfaces.
• Connective tissue binds and supports body parts.
• Muscle tissue makes movement possible.
• Nervous tissue conducts impulses helping with coordination.

Epithelial Tissue

• Epithelial tissue consists of tightly packed single (simple) to multiple (stratified) layers of cells that form protective barriers.
• It attaches to connective tissue using an acellular basement membrane.
• Various cell shapes include: squamous, cuboidal, and columnar.

Layers & Classifications of Epithelium

• Number of Layers or Category: Shape of Cells
• Simple (single layer of cells): Squamous, Cuboidal, and Columnar.
• Stratified (more than one layer of cells): Squamous, Nonkeratinized (moist), Keratinized, Cuboidal (very rare), and Columnar (very rare).
• Pseudostratified (modification of simple epithelium): Columnar.
• Transitional (modification of stratified epithelium): Roughly cuboidal to columnar when not stretched and squamouslike when stretched.

Connective Tissue

• Connective tissue is not as close together as epithelial tissue and it binds structures, provides support/protection, fills spaces, and transports blood cells.
• They are often widely scattered in a noncellular extracellular matrix.
• Connective tissue can secrete ground substance (liquid, medium for substance movement) and fibers (collagen and elastin).

Muscle and Nervous Tissue

• Muscle Tissue: Look for elongated cells, called muscle fibers, responsible for contraction and relaxation
• Skeletal muscle is voluntary, contains nuclei, and has clear striations.
• Smooth muscle is involuntary, not striated, and has a fusiform shape.
• Cardiac muscle is involuntary, striated, and has intercalated discs.
• Nervous Tissue consists of two cell types: neurons and neuroglia.
• Neurons contain a cell body, axon, and dendrites.
• Neuroglia is more abundant and provides supportive and protective functions without conducting impulses.

Cheek Cell Experiment

• Use KimWipes to clean the microscope.
• Sign the safety sheet before starting the lab.
• Follow disposal directions from the lab sheet.
• Dispose of slides in the labeled container, toothpicks and pipettes in biohazard waste, and methylene blue waste in its container.
• Record observations, be cautious with the stain, and leave out the microscope.

Additional Slides to Sketch

• Sketch the muscle (all 3 types: skeletal, smooth and cardiac), epithelial (all 3 shapes: squamous, cuboidal, and columnar, at least one stratified), and onion tip slide looking for PMAT stages.
• Sketch the connective tissues (blood, elastic, hyaline, tendons, fibro, and compact bone).
• Fill in all Assessment B’s for connective tissue and muscle/nervous lab sections.
• You will be able to distinguish between the 3 types of muscle tissue, epithelial and connective tissue.
• These features what you will need to know and handout.