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Plant Cells
Bot 101
Botany: A Human Concern
Robert Hooke first described cells
In 1663
Cells Organelles and Membranes
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Cells and Cell Theory
Prokaryotic Cells and Binary Fission
Eukaryotic Cells and Mitosis
Plasma Membranes
Organelles
Hooke studied the structure of cork.
Thought it looked like the rooms that
monks lived in at that time, called cells.
The name stuck
Generalized Prokaryotic Cell
Cell Theory
Capsule (sheath)
Three general principles
ribosomes
Cell wall
1. All living things are composed
of one or more cells
2. Cells are the smallest units of
life; chemical reactions
needed for life take place in
cells
3. All cells arise from preexisting cells
Plasma membrane
DNA (circular strand)
flagellum
Internal Membranes
Reproduction in Prokaryotes
Binary fission
• DNA replicates
• attaches to pm
• growth of pm
and cell wall
• pm pinches off
• two identical
cells
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Basic Plant Cell Structure
10 cell wall
20 cell wall • inside of 10 cell wall
• outside of
• cellulose and lignin
membrane
• not all cell types
• cellulose
nu
t
as
pl
ro
lo
h
c
vacuole
pits fields
tonoplast
mitoch
ondrion
w/ plasmodesmata
Organelles and other cell structures
Nucleus
• control center
• contains DNA
• carries genetic code
Mitochondria
• power house of cell
• contains ribosomes
• circular strand of DNA
• site of aerobic respiration
• produces chemical energy (ATP)
Cytoplasm – semi-fluid contents of a cell, excluding the
nucleus; mostly water
• pool of raw materials
Replication Division
in Eukaryotes
interphase
Two steps:
1. Mitosis – division of nucleus
• Interphase – DNA replicates
• Prophase – DNA condenses
• Metaphase – Chromosomes
line up on equator
• Anaphase – Chromatids are
pulled to opposite poles
• Telophase – two identical
nuclei form
2. Cytokinesis – division of
cytoplasm
new cell wall forms creating two
identical daughter cells
prophase
metaphase
Anaphase
Telophase and cytokinesis
Interphase
two identical daughter cells
Plastids
Chloroplast
• site of photosynthesis
• circular DNA
• ribosome
•2 membranes
Chromoplasts
• contain pigments
• provides color
in flowers and fruits
Leucoplasts
• store starch
Membranes are phospholipid bilayers that regulate the
passage of materials into and out of a cell.
Ribosomes – bead-like clusters of RNA and protein
• site of protein synthesis
Endoplasmic reticulum (ER) – series of folded
membranes from nucleus to plasmamembrane.
• smooth ER – lipid synthesis and transport
• rough ER – protein synthesis; have ribosomes
on surface
Golgi apparatus – series of flattened membranous sacs.
• processing and packaging proteins
• secretion
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Cell Walls – provides support for cells and determine shape
Onion cell wall with
plasmodesmata
Next time:
The Plant Body
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