1. Nucleic Acids and Cell Reproduction

2. Nucleic Acids Organic Compound 2 types of nucleic acids:
DNA: deoxyribonucleic acid
RNA: ribonucleic acid
Carries genetic material

3. Nucleotide
Is the monomer (small molecule) that makes up a nucleic acid
Made of a phosphate group, deoxyribose (5 carbon sugar) and a nitrogen base

4. They are complementary
Nitrogen bases in DNA:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
A and T always bond
C and G always bond
They are complementary

5. DNA Model Constructed in 1953 James Watson- Biologist from US
Francis Crick- Biophysist from England
Discovered the double helix model
Looks like a twisted ladder
Backbone of sugars and phosphates
Nitrogen bases make “rungs” of ladder
Held together by weak Hydrogen bonds

7. Purines: Adenine and Guanine
Double Ringed Nitrogen Bases
Pyrimidines: Cytosine and Thymine
Single Ringed Nitrogen Bases

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9. DNA Replication DNA makes exact copies of itself
Happens every time a cell divides
Steps of replication:
DNA unwinds by using the enzyme DNA helicase
DNA polymerase adds new bases beginning at the replication fork
DNA polymerase edits for errors

11. RNA Ribonucleic Acid Structure Three types of RNA: RNA Base Pairs:
C & G A& U
Ribonucleic Acid Structure
Single strand
Ribose
Uracil instead of Thymine
Uracil pairs with Adenine
Three types of RNA:
mRNA: Messenger RNA
tRNA: Transfer RNA
rRNA: ribosomal RNA

12. Gene Expression Taking information from DNA and making proteins
Uses all three types of RNA
Happens in two stages:
Transcription (writing): information is given to mRNA from DNA
Translation (telling): mRNA uses the information to make proteins

13. Transcription (Writing)
DNA is giving the information to the mRNA
Happens in the nucleus
~Terms to Know~
RNA polymerase: Enzyme that tells transcription to begin
Promoter: A sequence of DNA that acts like a green light for transcription
Terminator: a sequence of DNA that acts like a red light for transcription

14. Process Happens in the nucleus
RNA polymerase binds to the promoter (green light) on the DNA molecule.
The polymerase moves down the DNA strand adding complementary bases for the new RNA molecule
A bonds with T -C bonds with G
Polymerase adds bases until it reaches the terminator (red light)
A new mRNA strand is formed

15. mRNA
The mRNA that was formed in transcription has the following functions:
Carries heredity information to the site where proteins are made (ribosomes)
Is a template when amino acids are made
Amino acids are made according to the instructions found on this mRNA strand

16. Translation (telling)
mRNA carries information to the ribosome
In the cytoplasm
Where proteins are made
rRNA is a structural portion of the ribosome
mRNA then gives the information to tRNA
tRNA acts like a translator, changing the information into amino acid sequences
Proteins are then made from these sequences

17. Codon Three nucleotide sequence found on tRNA
These three nucleotides stand for an amino acid
Specific codons code for specific amino acids
Example:
tRNA codon- AGC Amino acid-Serine
tRNA codon-AAU Amino acid-Leucine
tRNA codon-UUU Amino acid-Lysine
AUG is a Start Codon- Where translation begins
UAA, UGA, or UAG are stop codons- Where translation ends

18. Some things to remember…
Proteins are made of amino acids
Proteins are made on ribosomes (floating in cytoplasm or embedded in rough ER)
Proteins are enzymes
Proteins also make up hair, skin, parts of blood, muscles…etc

20. Comparison of DNA and RNA
1. Double Stranded
Single Stranded
2. Thymine
Uracil
3. Nucleus
Cytoplasm
4. Deoxyribose sugar
Ribose sugar

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23. Chromosomes Genetic information is carried in DNA as chromosomes
Rod-shaped
Occur in pairs-
Homologous pairs (same size and shape)
Cells have specific numbers of chromosomes
Cells with both chromosomes are diploid (2N)
Humans 46 chromosomes •23 pairs
Cells with one chromosome of the pair are haploid (N)
Humans 23 chromosomes (sperm and egg)

24. Chromosomes…cont.
Autosomes: Chromosomes other than sex chromosomes (first 22 pairs-44 total)
Sex Chromosomes: Determines the sex of the individual (23rd pair-2 total)
XY= Male -XX= Female

25. Karyotype
Karyotype: Picture of paired human chromosomes arranged by size

26. Mitosis Cell division that results in two exact daughter cells
There is an exact replication of the nucleus
Cell Cycle:
G1 Phase: Cell growth
S Phase: DNA Replication
G2 Phase: Growth and prep. for mitosis
Mitosis: nucleus is divided into two cells
Cytokinesis: Cytoplasm divides

27. Anaphase Telophase Cytokinesis
G1 S G2
Prophase Metaphase
Anaphase Telophase Cytokinesis

28. Interphase G1, S and G2 phases Period between cell divisions
DNA is replicated
Time for growth and normal cell activities
Centriole divides and starts to move

29. Prophase
Metaphase
Anaphase
Telophase
PMAT

30. Prophase Centrioles move to opposite sides of cell
Chromosomes become thicker and coil
Spindles form
Nuclear membrane and nucleolus disappear

31. Metaphase The two centrioles are at opposite poles
The paired chromosomes line up in the MIDDLE
Centromere attaches to spindles

32. Anaphase
Chromatids separate
Chromosomes move to opposite poles

33. Telophase Chromosomes un-coil Spindles disappear
Nuclear membrane and nucleolus re-appear
Cytokinesis begins
Cytoplasm divides

34. Meiosis Occurs in sex cells (gametes-sperm and egg cells)
Only occurs in organisms that reproduce sexually
Same steps as mitosis, except process is completed twice
Divides chromosome number in half
2n (diploid) to n (haploid)

35. Results in 4 gametes
Spermatozoa: Sperm
Ova: Egg

36. Sexual vs. Asexual Reproduction
Sexual Reproduction: Need a sperm and egg cell
Genetic diversity
Species can adapt (change) for environment quickly
Slow population growth
Asexual Reproduction: Can reproduce without a partner
No genetic diversity
Quick reproduction, may be good for survival rates but organism will run out of resources quickly

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