Cells and Their Functions Chapter 3

Objectives List 3 types of microscopes Describe the function and composition of the plasma membrane Describe the cytoplasm and the organelles Describe the composition, location, and function of DNA Compare the 3 functions of RNA Explain briefly how cells make proteins Name and briefly describe mitosis Define 8 methods by which substances enter and leave the cell Explain what happens if cells are placed in solutions with the same concentration as the cell fluid and different as the cell fluid Define cancer List several risk factors for cancer

Basic unit of all life. The study of cells is cytology.

Cell Structure Plasma Membrane

Cell Structure Nucleus

Cell Structure Cytoplasm

Cell Structure Organelles – ER,ribosomes,mitochondria,Golgi apparatus,lysosomes,vesicles

Protein Synthesis Carries genetic message Located in nucleus DNA Carries genetic message Located in nucleus Composed of nucleotides Double-stranded - They are segments that make up our chromosomes

Cell Division Serves for growth, repair, and reproduction Meiosis : Chromosome number divided in half (forms the sex cells) Mitosis : Cell division that results in 2 identical daughter cells (exactly like parent cell)

Meiosis First, cuts the chromosome number in half to prepare for the union of the sperm and egg You need the reduction in chromosome number to have offspring with the right number.

Mitosis Continuous process, but distinct stages can be identified: All our somatic (body) cells divide this way.

Movement of Substances across the Plasma Membrane Some substances can enter the cell, others can not. The plasma membrane serves as a barrier between the cell and its environment. Separated into: movement that requires energy movement that does not require energy

Movements cont…. - Does NOT require energy Diffusion – constant mvmt of particles from higher concentration to lower Osmosis – special type of diffusion for water (move from an area where there are fewer solutes to one where there are more solutes) Filtration – passage of water through membrane due to a force Facilitated Diffusion – movement across membrane from higher to lower using transporters - DOES require energy Active transport – plasma membrane moves particles in or out in opposite direction Endocytosis – moves into cell (Phagocytosis, Pinocytosis) Exocytosis – moves out in vesicles

Solutions you need to know….

Cancer is defined as a tumor that spreads to other tissues. Also known as a malignant neoplasm.

Risk Factors for Cancer Heredity Chemicals Ionizing Radiation Physical Irritation Diet Viruses

Understanding… Your understanding of cell structure and function will help you to understand tissues, organs, systems and the whole human body!