A2.2 Cell Structure

Cell Theory

Cell Theory

• All living things are made of cells

• Cells can only arise from other pre-existing cells

• Cells are the smallest unit of life

What structures do all cells have?

Plasma membrane, cytoplasm, genetic material, ribosomes, cilia/flagella

Cell wall function

Maintains shape of the cell

Plasma membrane function

separates the internal and external environment of the cell and is selectively permeable

Cytoplasm function

Provides space for organelles to do work

Ribosomes functions

Synthesize proteins

Genetic material (DNA/RNA) function

Allows cells to produce proteins to perform functions of life

Mitochondria function

Produces ATP for the cell to perform living functions

Rough Endoplasmic Reticulum function

transports and finishes biological molecules like proteins

Smooth Endoplasmic Reticulum function

makes lipids and detoxes

Golgi Apparatus function

processes proteins, labels products with glycoproteins

Vesicles function

Storage and transport

Lysosomes functions

Digestion and breaking down waste products

Cytoskeleton function

Helps cell maintain its shape

What organelle is only present in animal cells?

Lysosomes, centrioles, cilia/flagella

What organelles are only present in plant cells?

Chloroplast, central vacuole, and cell wall

Chloroplast Function

Performs photosynthesis

Vacuole Function

Stores or expels water from the cell

Processes of Life in unicellular organisms

Reproduction, maintaining homeostasis, growth, excretion, movement, response to stimuli

Fungi Cell structure

Cell walls made of chitin, no chloroplasts, grow without light/oxygen

Atypical cell structure examples

Muscle cells, red blood cells, aseptate fungal hyphae, Phloem sieve tube cells

Muscle cells structure

Striated, multi-nucleated, large in size

Red blood cells structure

No nucleus, bioconcave shape, absence of organelles

Aseptate fungal hyphae structure

Multi-nucleated, continuous cytoplasm/multiple units, chitin cell walls

Phloem sieve tube cells structure

Lack of nucleus and organelles

Origin of cells by endosymbiosis

Larger eukaryote engulfed smaller prokaryote, leading to the development of the chloroplast/mitochondria

Evidence for endosymbiosis

Mitochondria and Chloroplasts have a double membrane, 70S ribosomes, divide by binary fission, and have circular DNA that is separate from the rest of the cell

Cellular Differentiation

The expression of specific genes to carry out specific functions