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Genetics
•Mitosis
•Semi-conservative Replication
•Protein Synthesis
Basic Unit of Life
• Cells
• Made of
– outside (cell membrane)
– Inside (cytoplasm and organelles)
• Governed by genetic material (DNA)
– DNA wrapped in a membrane = nucleus
• Characteristic of EUKARYOTIC cells (plants, animals, fungi,
protists, etc)
– DNA loose in cytoplasm = nucleoid region
• Characteristic of PROKARYOTIC CELLS (Bacteria)
Are their cells different?
Cell Size
• Cells cannot grow to unlimited size
• Nucleus cannot control movement into and
out of cell membrane
• Not enough of assorted organelles to get
necessary work done (proteins made, waste
removed, etc.)
• Key is surface area to volume ratio
Fill in the data chart
S = width of one side
S2 = surface area of one side
X 6 = total surface area
S3 = volume
Surface area to volume ratio
Cells divide so they don’t get too big.
• Requires copies of all cell contents including DNA
• DNA copies by semi-conservative replication.
– Each strand is half old and half new.
• MITOSIS: Basic cell division for growth and repair.
– Interphase (G1, S and G2)
– M phase:
Prophase, Metaphase, Anaphase,
and Telophase …
– followed by Cytokinesis
– Results in two “daughter” cells
DNA Song
• We love DNA made of nucleotides
– Really, what’s a nucleotide made of
• Sugar, phosphate and a base bonded down
one side
– What are the bases?
• Adenine and thymine make a lovely pair
• Cytosine without guanine would seem very
bare
• Oh, de-ox-y-ri-bo-nu-cleic acid
• RNA is ri-bo-nu-cleic acid
DNA Replication
• DNA must be copied so every new cell has the
same number and same kind of chromosomes
as every other cell.
Semiconservative
Replication
Strands separate
Bases are added
New DNA is half old,
new
half
Protein Synthesis
• DNA directs cell process through the
production of proteins
– Proteins are used for muscles, hormones,
enzymes, etc.
• Protein “synthesis” means to make a protein
• Occurs in two steps
– 1) transcription: occurs in nucleus
– 2) translation: occurs in cytoplasm at ribosome
Transcription
• DNA unzips
• Nucleotides are added to
form a “messenger” RNA
molecule (mRNA)
• mRNA leaves nucleus
through nuclear pore
Translation
• Messenger RNA travels to ribosome
• Three bases sequences on RNA are called
codons
– Ex:
AAC
GUA
AAC
GCC
AUC
• Transfer RNA molecules (tRNA) bring amino
acids to ribosome that match the codon on
the mRNA.
AGC UCU GCC AAA CAG UCU GUA CAA GGU UAA