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Structures and Functions

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Presentation on theme: "Structures and Functions"— Presentation transcript:

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

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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

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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

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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

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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

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