1. Structures and Functions
CELLS
Structures and Functions

2. Basic Parts of the Cell
Plasma membrane – barrier between in and outside of cell
Cytoplasm – region inside plasma membrane
Cytosol – includes molecules and small particles but not organelles
Genetic material
Ribosomes

3. Organelles! Eukaryotic Cell
Nucleus

4. The Nucleus Most obvious structure (5μm)
Most eukaryotic cells contain a nucleus
Function:
Controls most functions of cell
Houses and protects genetic information
Structure:
Nuclear envelope – double membrane layer contains genetic contents; porous – materials enter and exit
Nucleoplasm – jelly like fluid filling nucleus
Nucleolus – dense area where ribosomes are made

5. Processes:
Cell Division
When cell is not dividing - DNA exists as chromatin: long, thin structures
When cell is about to divide - DNA condenses to form chromosomes: structures made of DNA and protein
Transcription – DNA converted to RNA in the nucleus

7. Chromatin
Cell Division
Chromosome

8. Mitochondria

9. Mitochondria Size: 1-10 μm long Function:
Transfer energy from organic molecules to adenosine triphosphate (ATP) – powers most cellular reactions
Structure: inner & outer membrane
Outer – separates mitochondria from cytosol
Inner – many folds (cristae) that capture and store energy
Mitochondrial DNA – have own DNA
THEORY: mitochondria originated from prokaryotic cells

10. Processes:
Cellular respiration – enzymes in matrix aid in formation of ATP by extracting energy from food sources

11. Ribosomes

12. Ribosomes small, spherical (< 25 nanometers) Function:
Build proteins
Free ribosomes – make proteins used in cytosol (Ex: enzyme)
Bound ribosomes – make proteins used in membranes, packaging, and elsewhere in body
Structure:
Manufactured partly in nucleolus (protein & RNA), completed in cytoplasm
Have small and large subunit

14. Endoplasmic Reticulum

15. Endoplasmic Reticulum (ER)
System of cisternae - membranous tubes & sacs
Continuous with nuclear membrane
Function – moves molecules from one part of the cell to another
Structure – Rough and Smooth
Rough ER – covered with ribosomes; involved in making proteins
Secretory proteins – secreted in vesicles (Ex: digestive enzymes)
Membrane proteins – inserted in membranes
Smooth ER – no ribosomes; builds lipids, produces steroid hormones, detoxifies drugs and poisons

17. Golgi Apparatus

18. Golgi Apparatus System of cisternae stacked up Function:
Manufacturing, warehousing, sorting, shipping
Work with nearby vesicles coming from ER – vesicle contents modified, given “address label (carbohydrate label),” transported to other parts of cell
Structure:
Distinct polarity – membranes on opposite ends have different thickness & molecular composition
Two poles:
Cis (same side) – receives materials from ER
Trans (opposing side) – vesicles bud off & are transported/exported

20. Vesicles Small, spherical shaped sacs Function: Structure:
Migrate to and merge with cell membrane
Release contents outside of cell
Structure:
Single membrane
Different types (lysosomes, peroxisomes)

21. Lysosomes
Structure – bud from Golgi, contain digestive enzymes – each vesicle is specific!
Function – Break down macromolecules (proteins, carbohydrates, nucleic acids)
Processes:
Autophagy – Digestion of worn-out organelles
Autolysis – Digestion of damaged or extra cells when time for cell to die
Phagocytosis – Cell eating
Receptor-mediated endocytosis

22. Vesicles

23. Peroxisomes
NOT produced in Golgi, contain different enzymes, such as Catalase
Different types: Ex: Detoxify alcohol and other drugs
Break down fatty acids

24. Vacuole Membrane bound storage structures, contains fluid Types:
Food – stores nutrients
Contractile – contract, dispose of excess water

25. Vacuoles
Centriole

26. Centrioles Animal cells ONLY! Organize cell structure during division
2 short cylinders of microtubules

27. Part of cytoskeleton

28. Cytoskeleton Provides shape and support 3 structural elements
Microfilaments (Actin)- 2 strands intertwined; POLAR – can be used in cell movement, muscle contraction, cell division
Intermediate fibers – NONPOLAR - anchor nucleus and other organelles in place, maintain shape
Microtubules – hollow tubes made of maintain cell shape, hold organelles in place, POLAR – used in movement of chromosomes during division & organelles (like a railroad track) via the use of kinesins