Download Cells - Part 2 Nucleus

Chapter 3, Part 2 – Cellular Organelles!
Cells - Part 2!
Cells and Related Functions!
•  Organelles (“little organs”)!
•  Cell Cycle/Cell Division (Ch. 19, pp. 394 - 398)!
•  DNA Replication (Ch. 21, pp. 434 - 436)!
•  Protein Synthesis (Ch. 21, pp 436 - 441) !
•  Enzyme function (Ch. 2, pp. 31 - 32) !
1!
Nucleus!
Considered “the brain of the cell”!
Surrounded by double membrane!
•  Nuclear envelope with nuclear pores!
Contains:!
•  DNA in chromosomes!
" "Genes are instructions for building proteins!
" "23 pairs of chromosomes in humans!
•  RNA and proteins!
•  Nucleolus!
2!
1!
Chapter 3, Part 2 – Cellular Organelles!
Nucleus "
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Figure 3.13!
Rough ER!
!
Nucleus!
Nucleolus!
Nucleoplasm!
Nuclear!
envelope!
Chromatin!
Nuclear!
pores!
3!
Nucleolus"
"
"
"
"!
Found within the nucleus!
Does not have its own
membrane!
Contains:!
•  DNA + rRNA + ribosomal
proteins, enzymes!
•  Ribosomes are
assembled here!
Nucleus!
(Martini 2004)!
Nucleolus!
4!
2!
Chapter 3, Part 2 – Cellular Organelles!
Ribosomes!
Sites of protein synthesis"
Composed of a large and a small ribosomal
subunit!
Contain ribosomal RNA (rRNA) + protein!
•  Free ribosomes: suspended in cytoplasm!
•  Fixed (bound) ribosomes: attached to
endoplasmic reticulum!
5!
Ribosomes
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Figure 21.7!
6!
3!
Chapter 3, Part 2 – Cellular Organelles!
Endoplasmic Reticulum!
Composed of intracellular membranes!
Two types have different functions: !
•  Rough ER (RER) - contains ribosomes !
•  Smooth ER (SER) - no ribosomes!
7!
Rough Endoplasmic Reticulum
Figure 3.15a!
8!
4!
Chapter 3, Part 2 – Cellular Organelles!
Rough ER – General Functions!
Has ribosomes attached"
Make proteins for…!
1. Secretion from cell!
2. Inclusion in cell membranes!
3. Inclusion in lysosomes!
Other functions:!
•  Intracellular transport!
•  Temporary storage!
9!
Smooth ER – General Functions!
No ribosomes attached"
!
1. Makes vesicles that transport proteins to Golgi
apparatus!
2. Synthesizes lipids!
3.  Storage area!
4.  Detoxification reactions in the liver!
10!
5!
Chapter 3, Part 2 – Cellular Organelles!
Golgi Apparatus Functions!
Acts like the Post Office:!
•  Sorts, packages,
delivers molecules!
Forms secretory vesicles!
•  Discharged by
exocytosis!
Forms new membrane
components!
Forms lysosomes!
11!
Golgi Apparatus
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Figure 3.17!
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6!
Chapter 3, Part 2 – Cellular Organelles!
Lysosomes!
Lysosomes!
Contain digestive enzymes used in:!
•  Digestion following phagocytosis/
endocytosis!
•  Autophagy (recycling)!
13!
Lysosome Functions
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"
"
Figure 3.17!
14!
7!
Chapter 3, Part 2 – Cellular Organelles!
Mitochondria "
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Figure 3.19!
Responsible for ATP production through aerobic
respiration (aerobic???)!
Matrix = fluid contents of mitochondria!
Cristae = folds in inner membrane!
15!
16!
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Chapter 3, Part 2 – Cellular Organelles!
Chromosomes, Cell Division:!
"Chapter 19: pp. 394 – 398!
DNA Replication, Protein Synthesis!
"Chapter 21: pp. 434 - 441!
17!
Nucleus Contains Genes on Chromosomes!
Surrounded by a nuclear envelope (a double
membrane)!
Communicates with cytoplasm through nuclear
pores in the envelope!
Contents of the nucleus:!
•  Enzymes, nucleotides (DNA, RNA), ions, etc.!
•  One or more nucleoli!
•  Chromosomes!
18!
9!
Chapter 3, Part 2 – Cellular Organelles!
Cell Division!
Cell division is the reproduction of cells!
"1. Mitosis is the nuclear division of somatic cells!
"2. Meiosis produces sex cells!
•  We’ll cover this with Reproduction.!
19!
Cell Cycle
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Figure 19.2!
Withdrawal from cell cycle!
Mitosis!
20!
10!
Chapter 3, Part 2 – Cellular Organelles!
DNA Replication
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Figure 21.2!
A is complementary to T!
G is complementary to C!
!
It’s that simple (for this
class). Really!!
!
DNA polymerase (an
enzyme) knows how to do
this.!
!
How does this base pairing
scheme differ from that
seen in RNA??!
21!
The Genetic Code for Protein Synthesis!
A triplet code on DNA (and later, on RNA)!
•  Three nitrogenous bases in sequence
along a DNA strand code for one amino
acid.!
•  The information is transcribed to mRNA and
carried to the ribosome.!
A gene contains all the triplets needed to code
for a specific polypeptide!
•  DNA contains code"
•  mRNA contains codon"
22!
•  tRNA contains anticodon"
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Chapter 3, Part 2 – Cellular Organelles!
The Genetic Code!
mRNA Codons"
Figure 21.5!
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Codon: Three bases in
sequence specify that a
particular amino acid will
be added to a growing
protein during protein
synthesis!
23!
Protein Synthesis Overview!
transcription!
DNA!
translation!
RNA!
Protein!
Transcription:!
•  Information stays in the same language
(A language of base pair sequences)!
Translation:!
•  Information is translated from base pair
sequences to amino acid sequences
(A language of amino acids)!
24!
12!
Chapter 3, Part 2 – Cellular Organelles!
Making Proteins Requires:
"
"
(1 of 2)!
1. Instructions:!
•  Genes (code) on DNA in the nucleus!
2. An assembly site:!
•  Ribosomes!
"rRNA (ribosomal RNA) + proteins located
in the cytoplasm!
3. Messenger - “Federal Express”:!
•  mRNA (messenger RNA) carries instructions
(codon) from the nucleus to ribosomes in
cytoplasm!
Making Protein Requires:"
"
"
25!
"(2 of 2)!
4. Raw materials:!
•  Amino acids in cytoplasm!
5. Transport of raw materials to assembly site:!
•  tRNA (transfer RNA) contains anticodon and
carries amino acids to the assembly site
(ribosome)!
26!
13!
Chapter 3, Part 2 – Cellular Organelles!
Transcription!
Gene activation begins with RNA polymerase
binding to the gene (DNA)!
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Transcription is the formation of mRNA from DNA!
•  mRNA carries instructions from the nucleus to
the ribosome in the cytoplasm!
27!
Transcription "
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Figure 21.3!
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Chapter 3, Part 2 – Cellular Organelles!
Translation is the Formation of a Polypeptide!
A functional polypeptide is constructed from
information contained in mRNA codons"
The sequence of codons in mRNA determines the
the sequence of amino acids in a polypeptide!
Complementary base pairing with anticodons
(tRNA) provides the amino acids in the correct
sequence!
" "A is complementary to U!
" "C is complementary to G!
29!
Transfer RNA (tRNA)
"
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"
Figure 21.5!
amino acid!
Transfer RNA - carries amino!
acids to the ribosome!
AAA - anticodon on tRNA!
UUU - codon on mRNA!
30!
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Chapter 3, Part 2 – Cellular Organelles!
Translation Process - 1
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"Figure 21-8a!
Step 1:!
Small subunit binds!
mRNA at start
sequence!
site!
31!
Translation Process – 2 "
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Figure 21.8!
Step 2:!
!
•  tRNA with with !
complementary !
anticodon binds !
START codon!
!
•  Ribosomal subunits !
unite!
32!
16!
Chapter 3, Part 2 – Cellular Organelles!
Translation Process – 3 "
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Figure 21.9!
33!
Translation Process – 4 "
"
"Figure 21.11!
Termination of translation process!
34!
17!
Chapter 3, Part 2 – Cellular Organelles!
35!
36!
18!
Chapter 3, Part 2 – Cellular Organelles!
Cell Differentiation!
The process of specialization!
•  Cells take a “career path”!
Results from inactivation of particular genes!
Produces populations of cells with limited
capabilities!
Differentiated cells form tissues!
37!
Protein Synthesis Animations!
Protein synthesis animation #1!
•  https://www.biostudio.com/
demo_freeman_protein_synthesis.htm!
Protein synthesis animation #2!
•  https://www.youtube.com/watch?
v=Ikq9AcBcohA!
If you find a really useful one on the web, please
send me the link!
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19!
Chapter 3, Part 2 – Cellular Organelles!
Enzymes are Biochemical Catalysts!
Enzymes:!
1. Speed up chemical reactions that would
normally occur!
2. Not permanently changed by the reaction!
3. Work in both directions!
" "A + B ↔ A-B!
4. Are selective/specific!
5. Work best in certain (optimal) environment
"Temperature, pH, salinity, etc……!
6. Can be saturated!
39!
Enzymes!
Figure 2.25!
40!
20!