1. Biology STAAR Review #2 DNA / RNA / Protein Cell cycle Mitosis Meiosis
Replication
Transcription
Translation
Mutations
Cell cycle
Mitosis
Meiosis

2. The Genetic Code: DNA – code for all life – in all cells
DNA coils to form Chromosomes
A Gene is a section of DNA
Genetic info is encoded in sequence of base triplets, called codons
All cells contain Chromosomes
Chromosomes are made of DNA
Sections of DNA which code for genetic information are called genes

3. Virtually all organisms share the same genetic code “unity of life”
Organism’s genotype is carried in its sequence of bases

4. DNA – nucleic acid long chains of nucleotides
Nucleotide: 3 parts
Phosphate
Sugar
Nitrogen Base
G, C, A , T

5. Partial chemical structure
DNA –
double strand – twisted ladder or double helix
Hydrogen bonds between bases hold strands together:
A with T and C with G
Hydrogen bond
Ribbon model
Partial chemical structure
Computer model

6. Nitrogenous base (A, G, C, or U)
RNA is also a nucleic acid
different sugar, ribose
U instead of T
Single strand
Nitrogenous base (A, G, C, or U)
Phosphate group
Uracil (U)
Sugar (ribose)

7. DNA Both RNA Nucleic acid Double Strand Nucleotides Single Strand
Thymine
Nitrogen bases
Uracil
Sugar = Deoxyribose
Sugar
Sugar = Ribose
Controls protein synthesis
Controls heredity
Phosphate
Replicated before cell division
Leaves nucleus
Single strand Nucleotides Uracil Thymine Phosphate
Replicated before cell division Controls protein synthesis Sugar
Sugar=deoxyribose Nucleic acid Double strand Leaves nucleus Controls heredity Sugar=ribose Nitrogen bases

8. Replication: DNA → DNA each strand is a template for a new strand
Occurs in nucleus – before cell division
Produces 2 identical double helixes
Purpose: Cell division, reproduction, growth
Figure 10.4B

9. Transcription: DNA → _____
mRNA
Transcription: DNA → _____
One strand serves as template
Occurs in nucleus
Produces single strand
Purpose: transfers genetic code for protein synthesis

10. Translation: mRNA → _______
Protein
Translation: mRNA → _______
mRNA leaves nucleus
Occurs in cytoplasm
Purpose: protein synthesis

11. Translation: mRNA → Protein
The “words” of the DNA “language” – 3 bases called codons
Sequence of amino acid chain = ________
Protein
Ribosome –
“reads” mRNA codon
tRNA –
brings matching amino acid
Amino acids
form chain to build protein

12. Codon coding for amino acids
thr
ACG = __________
Notice 3 other codons also code for same amino acid

13. Transcription and Translation - Recap
Nucleus
Cytoplasm
What is Replication?
DNA → DNA
Where does it happen?
Nucleus
Cell membrane
Ribosome

14. Mutations can change the meaning of genes
Mutations (Gene or chromosomal)
are changes in the DNA base sequence
caused by errors:
in DNA replication
by mutagens
environmental: UV radiation, chemicals, carcinogens
Can be helpful harmful or neutral (silent)
change of a single DNA nucleotide causes disease
Effect depends on
where mutation occurs
1. type of cell
a. body (somatic)
b. sex cell – passed to offspring
2. type of mutation

15. Gene Mutations Point – changes only 1
Substitutions = 1 nucleotide changed
UGC to UGA
Inversion= reverse order
UGC to CGA
Frameshift – changes all after
Insertions = nucleotides added –
Deletions = nucleotides deleted –
UGC to UGGC
UGC to UC

16. Chromosomal Mutations – large chunks affected
Deletion - (whole or part deleted)
Insertion - (additional part added)
Duplication - (extra copies of parts)
Inversion - (reverses parts of chromosomes)
Translocation - (parts break off and relocate)

17. The Cell Cycle

18. Five Phases of the Cell Cycle
G1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
M - mitosis
C - cytokinesis
Collectively these 3 stages are called Interphase

19. Interphase - G1 Stage 1st growth stage after cell division
Cells mature by making more cytoplasm & organelles
Cell carries on its normal metabolic activities

20. Interphase – S Stage Synthesis stage DNA is copied or replicated
Two identical copies of DNA
Original DNA

21. Interphase – G2 Stage 2nd Growth Stage Cell gets ready for division
Copied DNA – checked for mistakes & repaired
All cell structures needed for division are made (e.g. centrioles)
Both organelles & proteins are synthesized

22. Cell cycle Grows & makes organelles & cytoplasm Doubles DNA
Checks & repairs DNA errors

23. Mitosis: Identical Daughter Cells
Two identical daughter cells
Parent Cell

24. Mitosis: Cell Division
Used for growth and repair
Produce two new cells identical to the original cell
Cells are diploid (2n)
Chromosomes during Metaphase of mitosis
Cytokinesis
Anaphase
Prophase
Metaphase
Telophase

25. Mitosis 1. Prophase: 2. Metaphase: 3. Anaphase: 4. Telophase:
4 stages:
1. Prophase:
The Centrioles begin to move apart.
Chromosomes thicken
The Nuclear membrane disappears
2. Metaphase:
The centrioles are at the “poles” of the cell
The chromosomes line up in the middle of the nucleus
3. Anaphase:
The Chromosomes are pulled toward the centrioles by spindle fibers
4. Telophase:
The nucleus begins to reform and the cell begins to split - cytokinesis

26. Prophase Metaphase Anaphase Telophase Four Mitotic Stages
What are stages? 1 2
Prophase
Metaphase
Anaphase
Telophase 3 4

27. Name the Stages of Mitosis:
Early prophase
Early Anaphase
Metaphase
Interphase
Early Telophase,
Begin cytokinesis
Late Prophase
Late telophase,
Advanced cytokinesis
Mid-Prophase
Late Anaphase

28. ? ? ? ? ? ? ? Identify the Stages Early, Middle, & Late Prophase
Metaphase
Anaphase
Late Prophase ? ? ?
Late Anaphase
Cytokinesis
Telophase

29. Cell Division Mitosis Meiosis Cells divide for two reasons.
1. To create copies -
Mitosis
Meiosis
2. To create sex cells (gametes) -
sperm
egg

30. Mitosis: Identical Daughter Cells
2 chromosomes
Mother cell:
2 chromosomes
Chromosome number the same, but cells smaller than parent cell

31. Meiosis: Gamete - sperm or egg
The process of creating haploid sex cells called Gametes
Gamete
- sperm or egg
Has two phases of “Mitosis-like stages”
End result: Half the genetic material
For humans: cell with 46 chromosomes forms cells with ___ 23

32. Meiosis Forms Haploid Gametes
Meiosis must reduce the chromosome number by half
Fertilization then restores the 2n number
from mom
from dad
child
too
much!
meiosis reduces
genetic content
The right number!

33. Comparison of Divisions
Mitosis
Meiosis
Number of divisions
Number of daughter cells
Genetically identical?
Chromosome #
Where
When
Role 1 2 2 4
Yes No
Same as parent
Half of parent
Somatic cells body cells
Germ cells
Ovaries / testes
Whole life
At sexual maturity
Sexual reproduction Gametes (egg/sperm)
Growth and repair