1. 1-1: How does an understanding of DNA help us investigate living things?
Image credits: singularityhub.com
Any uncredited images throughout this powerpoint are from Science Connections 10 textbook or publisher’s powerpoint.

2. Big Ideas
The variation in living things we see around us is due to DNA.
DNA is made of many nucleotides linked together in a specific order.
DNA exists in chromosomes, which contain thousands of genes.
The structure of DNA is important to passing on information.
The different genetic make-up of organisms is reflected in the diversity of living things.

3. Key Vocabulary DNA (deoxyribonucleic acid) Homologous chromosomes mRNA
tRNA
Genes
Transcription
Alleles
Nucleic acid
Translation
Karyotype
Nucleotide
Codon
DNA replication
Nitrogenous base
Anti-codon
Biodiversity
Cytosine
Genome
Species diversity
Guanine
Chromatin
Genetic diversity
Thymine
Ecosystem diversity
Adenine
Chromosome
Population
Complementary base
Sex chromosomes
Autosomes
Protein

4. Concept 1: The variation in living things we see around us is due to DNA.
All living things have DNA.
Variations among all organisms are due to DNA.
Figure 1.1: Life, variety, and
DNA. Questioning: What is
the role of DNA in the variety of Earth’s organisms? Do you think it is the only factor?

5. DNA What is DNA? Deoxyribonucleic acid
Concept 1: The variation in living things we see around us is due to DNA.
DNA
What is DNA?
Deoxyribonucleic acid
Double-stranded nucleic acid that stores genetic information in the nucleus
Inherited: passed on to future generations
Differences in DNA result in variations in characteristics and allow organisms to exist in diverse aquatic and terrestrial ecosystems.
Image credits: yourgenome.org

6. Example: Sickle Cell Anemia
Concept 1: The variation in living things we see around us is due to DNA.
Example: Sickle Cell Anemia
Summary: one base pair difference in DNA causes sickle cell anemia (a blood disease)
Slide from

7. Example: Brown vs Blonde Hair
Concept 1: The variation in living things we see around us is due to DNA.
Example: Brown vs Blonde Hair
Summary: one base pair difference causes blonde hair instead of brown
Image from:

8. Discussion Questions Why is there variation among organisms on Earth?
Concept 1: The variation in living things we see around us is due to DNA.
Discussion Questions
Why is there variation among organisms on Earth?
Choose one group of organisms in Figure 1.1 and describe some of the similarities and differences between species in that group. Use examples not already listed in the text.

9. Concept 2: DNA is made of many nucleotides linked together in a specific order.
There are two types of nucleic acids:
DNA (deoxyribonucleic acid)
RNA (ribonucleic acid)
All living things use one of the two types of nucleic acids as genetic information.
Nucleotides are the basic building blocks of nucleic acids.

10. The Structure of DNA Nucleotides consists of three components:
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Structure of DNA
Nucleotides consists of three components:
a phosphate group
a sugar
a nitrogenous base
Figure 1.2: Nucleotides are the basic building
blocks of DNA and RNA.

11. The Structure of DNA (cont’d)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Structure of DNA (cont’d)
Nitrogenous bases in DNA include:
adenine (A)
cytosine (C)
guanine (G)
thymine (T)
Fun fact: human genome has 3 billion base pairs split up into 46 chromosomes
Figure 1.2: Nucleotides are the basic building blocks of DNA and RNA.

12. The Structure of DNA (cont’d)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Structure of DNA (cont’d)
Characteristics of the DNA molecule:
Two strands of nucleotides
Twisted ladder (double helix) structure
Sides of ladder made up of sugar and phosphate groups
Rung of ladder is made of two nitrogenous bases held together by hydrogen bonds

13. The Structure of DNA (cont’d)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Structure of DNA (cont’d)
Nitrogenous bases that pair together are complementary bases:
adenine (A) and thymine (T)
cytosine (C) and guanine (G)
Remember: Apples in a Tree; Car in a Garage
Figure 1.3: DNA is found in the nucleus of a cell. The bases of the nucleotides pair only in specific ways.

14. The Function of DNA DNA stores genetic information.
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Function of DNA
DNA stores genetic information.
Parents pass their DNA on to their offspring.
DNA codes for specific proteins that are essential for life functions.
A complete sequence of DNA is called a genome.

15. Protein Synthesis: Summary
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Summary
Transcription:
DNA is transcribed into mRNA
Translation:
Ribosome reads mRNA
mRNA is translated into an amino acid sequence through tRNA
End result: protein!

16. Concept 2: DNA is made of many nucleotides linked together in a specific order.

17. Concept 2: DNA is made of many nucleotides linked together in a specific order.
Post-video Questions
Why can’t proteins be made directly from the DNA? Why is mRNA necessary?
Where do transcription and translation occur?
What is the role of tRNA?

18. Protein Synthesis: Transcription
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Transcription
Transcription:
Part of DNA is copied into messenger RNA (mRNA) transcript
RNA base pairs:
adenine – uracil (not thymine)
guanine – cytosine
Occurs in nucleus
Codon: 3-base-pair sequence in mRNA

19. Protein Synthesis: Transcription
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Transcription
Practice:
For the DNA sequences below, write the corresponding mRNA sequence.
TAC CAT TAA CAG TAC GGG (DNA)
AUG GUA AUU GUC AUG CCC (mRNA)
TAC ATG GCA ATA CGC GAA (DNA)
AUG UAC CGU UAU GCG CUU (mRNA)

20. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Translation:
mRNA leaves nucleus, is ‘read’ by ribosome
Transfer RNA (tRNA) has matching anticodon and amino acid
Result: amino acid chain = protein (basically!)

21. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
ib.bioninja.com.au

22. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Charts can help us determine the corresponding amino acids for mRNA codons.
Ibiologia.com; Georgia virtual school

23. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Charts can help us determine the corresponding amino acids for mRNA codons.

24. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Charts can help us determine the corresponding amino acids for mRNA codons.

25. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Practice:
For the mRNA sequences below, write the corresponding amino acid sequence.
AUG GUA AUU GUC ACA CCC (mRNA)
AUG UAC CGU UAU GCG CUU (mRNA)
Question: Why might both these mRNA sequences start with AUG?

26. Protein Synthesis: Translation
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis: Translation
Practice:
For the mRNA sequences below, write the corresponding amino acid sequence.
AUG GUA AUU GUC ACA CCC (mRNA) methionine – valine – isoleucine – valine – threonine – proline (met-val-ile-val-thr-pro)
AUG UAC CGU UAU GCG CUU (mRNA) methionine – tyrosine – arginine – tyrosine – alanine – leucine (met-tyr-arg-tyr-ala-leu)
Question: Why might both these mRNA sequences start with AUG?

27. Protein Synthesis Summary (copy down)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
Protein Synthesis Summary (copy down)
Step
Code
Extra Notes
DNA
TAC GAT
Complementary DNA strand (the one not used to make mRNA here) would be ATG CTA
mRNA
AUG CUA
U instead of T; codon
tRNA
UAC GAU
Complementary to mRNA; anti-codon
Amino acid
Met – Leu
(Methionine – Leucine)
Based off mRNA codon

28. The Many Functions of Proteins (do not memorize)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Many Functions of Proteins (do not memorize)
Proteins do everything that a cell (and thus, a living thing) needs to function, grow, and reproduce. This includes:
Structure
Growth and repair
Signalling to other cells or organisms
Facilitating or catalyzing chemical reactions
Shuttle substances across cell membrane

29. Concept 2: DNA is made of many nucleotides linked together in a specific order.

30. The Many Functions of Proteins (do not memorize)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Many Functions of Proteins (do not memorize)
Cool Proteins:
Protein type or name
Function
Sonic Hedgehog (SHH)
Controls stem cell growth in limbs
Keratin
Structural: makes up hair, feathers
Actin + tubulin
Clock proteins
Detects light; establish circadian cycle
Antibodies
Bind to harmful pathogens; help neutralize or tag for destruction
Hemoglobin
In red blood cells, stores oxygen or carbon dioxide
ATP synthase
A ‘turbine’ that harnesses proton gradient to make ATP

31. The Many Functions of Proteins (do not memorize)
Concept 2: DNA is made of many nucleotides linked together in a specific order.
The Many Functions of Proteins (do not memorize)
Cool Proteins:
Insulin
Collagen
Thrombin
Neuroreceptors (e.g. for GABAa, dopamine)
Potassium channel
Oxytocin
Histone

32. Concept 2: DNA is made of many nucleotides linked together in a specific order.
Discussion Questions
If the bases on one strand of DNA are ATGGGCTA, what is the sequence of complementary bases on the other strand of DNA?
Think of an analogy to describe base pairs. Share it with a classmate.

33. Concept 3: DNA exists in chromosomes, which contain thousands of genes.
During interphase, DNA exists as condensed fibers called chromatin.
During mitosis, DNA is found in a very condensed form called chromosomes.
Figure 1.4: DNA is part of chromatin fibre, which condenses to form chromosomes.

34. Chromosomes Are Paired
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Chromosomes Are Paired
46 chromosomes in human somatic (body) cells
Half from father, half from mother
23 pairs of chromosomes in total:
One pair: sex chromosomes (X and Y chromosomes)
Other 22 pairs: autosomes

35. Homologous Chromosomes Contain Alleles
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Homologous Chromosomes Contain Alleles
Homologous chromosome: a chromosome that contains the same sequence of genes as another chromosome
Inherit one set from each parent
Homologous chromosomes are not identical…they may have different alleles
Figure 1.5: Homologous
chromosomes have several
characteristics in common,
but they are not identical.

36. Homologous Chromosomes Contain Alleles (cont’d)
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Homologous Chromosomes Contain Alleles (cont’d)
Gene: a part of a chromosome that governs the expression of a trait and is passed on to offspring
Allele: one of multiple different forms of the same gene; usually represented by capital/lowercase letters
Gene Examples (simplified for illustrative purposes)
Allele Examples
Blondeness gene
Brown hair, blonde hair
Eye colour gene
Blue eyes, brown eyes
Lactase gene
Lactose tolerant, lactose intolerant

37. Homologous Chromosomes Contain Alleles (cont’d)
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Homologous Chromosomes Contain Alleles (cont’d)
Image:

38. Examining Chromosomes: The Karyotype
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Examining Chromosomes: The Karyotype
Karyotype: a photograph of pairs of homologous chromosomes in a cell
Figure 1.6: This is a human karyotype. The chromosome pairs are arranged and numbered in order of their length, from longest to shortest. The sex chromosomes are placed last.

39. Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Review: mitosis
In mitosis, each cell ends up with chromosomes that are identical to the parent cell (one copy of each homologous chromosome)
Source:

40. Review: meiosis + sexual reproduction
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Review: meiosis + sexual reproduction
Chromosome number halved
Independent assortment at metaphase I plate: only one of each homologous chromosome ends up in gamete
Thus: random inheritance of traits from parents
Image:

41. Preview: meiosis + sexual reproduction
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Preview: meiosis + sexual reproduction
Parental DNA
Fertilization (one chromosome from each parent)
Offspring DNA
Meiosis
Gametes
Biological father
100% chance of allele “a”
100%
Biological mother
100% chance of allele “A”
Images:

42. Preview: meiosis + sexual reproduction
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Preview: meiosis + sexual reproduction
Parental DNA
Fertilization (one chromosome from each parent)
Offspring DNA
Meiosis
Gametes
Biological father
50% chance of allele “A”; 50% of allele “a”
50%
Biological mother
100% chance of allele “A”
50%
Images:

43. Preview: meiosis + sexual reproduction
Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Preview: meiosis + sexual reproduction
Parental DNA
Fertilization (one chromosome from each parent)
Offspring DNA
Meiosis
Gametes
Biological father
50% chance of allele “A”; 50% of allele “a”
25%
25%
Biological mother
25%
50% chance of allele “A”; 50% of allele “a”
25%
Images:

44. Concept 3: DNA exists in chromosomes, which contain thousands of genes.
Discussion Questions
Describe the relationships among chromatin, a chromosome, DNA, and a gene.
Make an analogy that helps explain homologous chromosomes.

45. Concept 3: DNA exists in chromosomes, which contain thousands of genes.

46. Concept 4: The structure of DNA is important to passing on genetic information.
A cell replicates its DNA once in the cell cycle.
DNA is passed on to daughter cells, and to offspring, influencing all heritable characteristics

47. Cell Cycle Review G1 : Growth Performs regular cell functions
Concept 4: The structure of DNA is important to passing on genetic information.
Cell Cycle Review
G1 :
Growth
Performs regular cell functions
S: DNA replication
DNA replicated: one  two sister chromatids per chromosome
G2 :
Mitosis/cytokinesis: cell divides

48. Concept 4: The structure of DNA is important to passing on genetic information.
DNA Replication
Replication: a process that makes identical copies of a DNA molecule
Cytosine pairs with Guanine
Adenine pairs with Thymine
Each new DNA molecule consists of an original strand and a new strand.
Figure 1.7: During DNA replication, two molecules of DNA are made from one. The resulting new molecules are identical to the original. Each new molecule contains one original strand of DNA (shown here in blue) and one new strand (shown in red).

49. DNA Replication (cont’d)
Concept 4: The structure of DNA is important to passing on genetic information.
DNA Replication (cont’d)
DNA is used to produce RNA.
RNA is then translated to produce a protein.
The sequence of bases in the DNA molecule determines the specific sequence of amino acids in the protein molecule.
Figure 1.8: Genetic information passes from the genes (DNA) to an RNA copy of the gene, and the RNA
copy directs the sequential assembly of a chain of amino acids to produce a protein.

50. DNA Replication (cont’d)
Concept 4: The structure of DNA is important to passing on genetic information.
DNA Replication (cont’d)
DNA replication is complex, involving many enzymes (proteins!) and other molecules.

51. Concept 4: The structure of DNA is important to passing on genetic information.
Discussion Questions
Explain how the structure of DNA is related to how genetic material is passed from one generation to the next.
How are genes involved in the production of proteins?

52. Concept 5: The different genetic make-up of organisms is reflected in the diversity of life.
Biodiversity exists at three different levels:
species diversity
genetic diversity
ecosystem diversity
NOTE: Concept 5 is FYI only: not testable!

53. Concept 5: The different genetic make-up of organisms is reflected in the diversity of life.
Species Diversity
Species diversity: variety and abundance of species in a given area
Species: group of organisms that can interbreed in nature and produce fertile offspring

54. Concept 5: The different genetic make-up of organisms is reflected in the diversity of life.
Genetic Diversity
Genetic diversity: variety of inherited traits within a species; is due to mutations in genes.
Gene pool: genetic diversity within a population
Population: members of the same species living in the same geographical area at the same time

55. Concept 5: The different genetic make-up of organisms is reflected in the diversity of life.
Ecosystem Diversity
Ecosystem diversity: variety of ecosystems in the biosphere
Ecosystems are made up of biotic (living) factors and abiotic (non-living) factors.

56. Concept 5: The different genetic make-up of organisms is reflected in the diversity of life.
Discussion Questions
Describe the differences among the three types of biodiversity.
Explain how variation in genes is related to all three types of biodiversity.