Cells Chapter 3

Cell Structure Plasma membrane Cytoplasm: cytosol + organelles Nucleus

Figure 3.1

Cell Membrane Phospholipid bilayer Cholesterol Proteins attached carbohydrates

Figure 3.2

Membrane Function Barrier between inside and outside of cell Controls entry of materials- Transport Receives chemical and mechanical signals Transmits signals between intra- and extra cellular spaces Note the various proteins in figure

Terminology: Body Fluid Pools Intracellular (ICF) 2/3 of total Extracellular (ECF) -> Between cells = Interstitial In blood vessels = Plasma In lymphatic vessels = Lymphatic

Terminology: Solutions Solvent- doing the dissolving Mostly water Solute- material dissolved Concentration Amount of solute in a given amount of solvent Concentration gradient Difference in concentration between 2 areas of solution

Figure 3.3

Passive transport: Diffusion Requirements for Simple Diffusion Concentration gradient of solute Can diffuse across a membrane either dissolve in the lipid membrane e.g. O2, C O2, lipid soluble vitamins if charged must go through channels Specialized ion channels that can open and shut = (gated channels)

Figure 3.4

Figure 3.5

Facilitated Diffusion Requires a carrier in membrane Only goes down concentration gradient Saturates = maximum speed Maximum speed dependent on carrier number

Figure 3.6

Osmosis Diffusion of water Must have a membrane Membrane impermeable to a solute

Figure 3.7

Figure 3.8

Active Transport Requires a carrier Requires energy (ATP) Can transport up a concentration gradient Critical for moving important ions Major active transport in most cells = Sodium-potassium (Na+/K+) pump

Figure 3.9

Transport in Vesicles Requires energy Involves small membrane sac Endocytosis- importing materials Exocytosis- exporting materials

Cell organelles Table 3.2 Cytoskeleton- Fig 3.11 Flagella, Cilia & Centrioles- Motion Endoplasmic reticulum- Fig. 3.14 Golgi apparatus- Fig. 3-15 Mitochondrion- Fig 3-16 Nucleus, nucleolus, nuclear envelope- Fig. 3-17 Vesicles, e.g. lysosome-

Cytoplasm Cell contents Includes organelles and Cytosol Excludes nucleus

Cytoskeleton Maintain shape of cell locate organelles change cell shape Includes: microfilments, intermediate flilments, microtubules

Figure 3.11

Centrosome Centriole Pericentiolar material

Figure 3.12

Cilia and flagella Specialized for motion Flagella- single Cilia in groups Found in respiratory system- move mucus

Ribosomes Sites of protein synthesis Ribosomal RNA (rRNA) Ribosomal Proteins Can be attached to endoplasmic reticulum or free in cytosol

Endoplasmic Reticulum- Synthesis and intracellular transport lipid synthesis- all Protein synthesis- rough E.R. Protein modification transport around cell

Figure 3.14

Golgi Complex Modify and package proteins E.g. lipoproteins and glycoproteins Some packaged into vesicles=> Lysosomes or export by exocytosis

Figure 3.15

Small bodies Lysosomes- contain digestive enzymes Peroxisomes- oxidize for detoxification Abundant in liver Proteasomes- digest proteins

Mitochondrial function Energy (ATP) production Where oxygen is consumed where nutrients are “burned”

Figure 3.16

Nucleus Round or oval structure Surrounded by nuclear envelope Openings = Nuclear pores Can include a nucleolus- make ribosomes Store genetic material copy information for transfer to new cells to the cytosol for protein synthesis

Figure 3.17 part 1

Figure 3.17 part 2

Protein Synthesis 2 steps Nuclear = transcription Cytoplasmic = translation

Figure 3.19a

Figure 3.19b

Transcription In nucleus RNA polymerase transcribes DNA into RNA=> 1. messenger RNA (mRNA) Directs synthesis of polypeptide 2. Ribosomal RNA Part of ribosomes Transfer RNA (tRNA) Carries amino acids to ribosome for reaction

Translation Requires 3 different RNAs Message RNA -from nucleus (mRNA) Transfer RNA to carry amino acids (tRNA) Ribosomes to do the actual work containing ribosomal RNA (rRNA)

Figure 3.20

Figure 3.20 part 1

Figure 3.20 part 2

Figure 3.20 part 3

Figure 3.20 part 4

Figure 3.20 part 5

Figure 3.20 part 6

Cell Cycle Interphase Mitotic Phase = division of nucleus and cell Growth and development of cell prepare for reproduction-DNA synthesis,etc. Mitotic Phase = division of nucleus and cell 4 phases Cytokinesis= division of cell

Prophase Centrioles move to opposite ends Nuclear envelope disappears Chromosomes appear with centromeres Chromosomes move to spindles

Figure 3.21b

Metaphase Chromosomes lined up in center=> Metaphase plate

Figure 3.21c

Figure 3.21c

Anaphase Sister chromosomes move to opposite ends of spindle

Figure 3.21d

Telophase Nuclear envelopes reappear Cytokinesis is completed

Aging May be programmed genetically Number of factors contribute Protein cross-links by glucose Free radical damage Cessation of mitosis