Transcript Cell Structure and Function

Cell Structure and Function
Cells
• Smallest living unit
• Most are microscopic
Cell Size
Cells Have Large Surface
Area-to-Volume Ratio
Characteristics of All Cells
• Cell Membrane (Plasma Membrane)
• Cytoplasm – cell contents in thick fluid
• Control center with DNA
Cell Types
• Prokaryotic
• Eukaryotic
Prokaryotic Cells
• First cell type on earth
• Cell type of Bacteria and Archaea
Prokaryotic Cells
• No membrane bound nucleus
• Nucleoid = region of DNA concentration
• Organelles not bound by membranes
Eukaryotic Cells
• Nucleus bound by membrane
• Include fungi, protists, plant,
and animal cells
• Possess many organelles
Protozoan
Representative Animal Cell
Representative Plant Cell
Cytoplasm
• Viscous fluid containing organelles
• components of cytoplasm
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Interconnected filaments & fibers
Fluid = cytosol
Organelles (not nucleus)
storage substances
Nucleus
• Double membrane
filled with nucleoplasm
• Control center of cell
• Houses and protects
cell’s genetic info
• Control’s cells
functions
DNA
• Hereditary material
• Chromosomes
– DNA and protein
– Only visible when cell
is dividing (but present
all the time)
Nuclear Envelope and Pores
• Double membrane
• Separates nucleus
from rest of cell
• Has pores
• Allows only certain
materials to enter
and exit nucleus
Nucleolus
• Dark dense area inside nucleus
• Where DNA is concentrated when making
ribosomal RNA
Cell (Plasma) Membrane
• Double layer of phospholipids, proteins and
cholesterol
• Contains cell contents
• Controls what enters/exits the cell
Endoplasmic Reticulum
• Helps move substances within cells
• Network of interconnected membranes
• Two types
– Rough endoplasmic reticulum
– Smooth endoplasmic reticulum
Rough Endoplasmic Reticulum
• Ribosomes attached to surface
• Helps to move proteins around cell
• May modify proteins from ribosomes
Smooth Endoplasmic Reticulum
• No attached ribosomes
• Helps to make lipids
• Detoxifies and breaks down harmful
chemicals
Ribosomes
• Attached to ER or free floating in
cytoplasm
Golgi Apparatus
• Stack of flattened membranes
• Packaging & shipping station of cell
• Proteins go here after leaving ER and are
modified and shipped out of cell in small
sacs called vesicles
Lysosomes
• Small sac-like structures
• Contain digestive enzymes
• Functions
– Recycling centers
– Break down old cell parts
– Digests invaders
• Found in animal cells
Peroxisomes
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Small sac-like structures
Abundantly found in liver and kidneys
Help to detoxify
Names for the hydrogen peroxide they produce
as a waste from their reactions.
Mitochondria
• Break down sugars and
fats in cellular
respiration and release
energy in the form of
ATP
• Cells that need more
energy have more
Mitochondria
• Has its own DNA
(endosymbiotic
theory)
Cytoskeleton
• Filaments & fibers
– Microfilaments
– Microtubules
– Intermediate filaments
• 3 functions:
– mechanical support
– anchor organelles
– help move
substances
• Include cilia, flagella
and centrioles
Centrioles
• Pairs of microtubular structures
• Play a role in cell division
• Found only in animal cells
Cell Walls
• Found in plants – composed of cellulose
• Surrounds plasma membrane
• Provides support, strength and protection
Central Vacuoles
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Membrane bound storage sacs
In plants
Very large
Contents
– Water
– Food
– Wastes
*animals have small vacuoles
throughout cell
Chloroplasts
• Solar energy capturing organelle – carry
out photosynthesis
• Contain chlorophyll and are green
• Have their own DNA
Chromoplast
• Contain pigments
• Help capture more light energy for photosynthesis
• Help to make other parts of the plants other colors
(fruits, flowers, roots etc.)
End Chapter 5