Exam #3 Flashcards
1
Q
Mitosis
A
- The division of a single nucleus into two genetically identical nuclei (daughter cells)
2
Q
Prophase
A
- First stage of mitosis
- During which the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still intact
- Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres
- some fibers cross the cell t form the mitotic spindle
3
Q
Metaphase
A
- The third stage of mitosis, during which all the cell’s duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle
- Spindle fibers align the chromosomes along the middle of the cell nucleus
- Line referred to as metaphase plate
- ensure that in next phase, when chromosomes are separated, each new nucleus will receive one copy of each chromosome
4
Q
Anaphase
A
- The fourth stage of mitosis, beginning when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the ce
5
Q
Telophase
A
- The fifth and final stage of mitosis
- During which daughter nuclei form at the two poles of a cell
- Usually occurs together with cytokinesis
- Arrive at opposite poles of cell, and new membranes form around the dauter nuclei
- chromosomes disperse and are no longer visible under the light microscope
- spindle fibers disperse
6
Q
Cytokinesis
A
- The division of the cytoplasm to form two separate daughter cells
- Usually occurs in conjunction with telophase of mitosis
- Mitosis and cytokinesis make up the mitotic (M) phase of the cell cycle
7
Q
Meiosis
A
- In a sexually reproducing organism
- Division of a single diploid nucleus into four haploid daughter nuclei
- Meiosis and cytokinesis produce haploid gametes from diploid cells in the reproductive organs of the parent
8
Q
Gametes
A
- A sex cell
- A haploid egg or sperm
- The union of two gametes of opposite sex (fertilization) produces a zygote
9
Q
Zygotes
A
- The diploid fertilized egg
- Results from union of a sperm cell nucleus and an egg cell nucleus
10
Q
Cross-over events
A
- The exchange of segments between chromatids of homologous chromosomes during synapsis in prophase I of meiosis
- The exchange of segments between DNA molecules in prokaryotes
11
Q
Homologous
A
- Pairing at meiosis and having the same structural features and pattern of genes
12
Q
Chromosomes
A
- Threadlike, gene carryinig structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis
- The main gene carrying structure of a prokaryotic cell
- Consists of one very long piece of chromatin, a combination of DNA and protein
13
Q
Dominant allele
A
– the allele that determines the phenotype of a gene when the individual is a heterozygous for that gene
14
Q
Recessive allele
A
- An allele that has no noticeable effect on the phenotype of a gene when the individual is heterozygous for that gene
15
Q
Heterozygous
A
- Having two alleles for a given gene
16
Q
Genotype
A
- Genetic makeup of an organism
17
Q
Phenotype
A
- Expressed traits of an organism
18
Q
Allele
A
- An alternative version of a gene
19
Q
Monohybrid
A
- An experimental mating of individuals differing in a single character
20
Q
- Dihybrid cross
A
– an experimental mating of individuals differing in two characters
21
Q
Diploid
A
- In an organism that reproduces sexually
- A cell containing two homologous sets of chromosomes
- One set inherited from each parents
- A 2n Cell
22
Q
Haploid
A
- In the life cycle of an organism that reproduces sexually
- A cell containing a single set of chromosomes
- An n cell
23
Q
Sex-linked
A
- A gene located on a sex chromosome
- In humans, the vast majority of sex-linked genes are located on the X chromosomes
24
Q
Autosomal
A
- A chromosome not directly involved iin determining the sex of an organism
- In mammals, any chromosome other than X or Y
25
Codominance
- Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles
26
Replication
- Occurs in the nucleus
- Process of making an identical copy of a section of duplex (double-stranded) DNA, using existing DNA as a template for the synthesis of new DNA strands
27
Transcription
- The synthesis of RNA on a DNA template
28
Translation
- The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule
- There is a change of “language” from nucleotides to amino acids
29
Mutations
- Change in nucleotide sequence of an organisms DNA
- The ultimate source of genetic diversity
- Can occur in the DNA or RNA of a virus
30
Ribosomes
- Cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm
- In eukaryotic cells, the ribosomal units are constructed in the nucleolus
31
Genetic code
- Set of rules that dictates the correspondence between RNA codons in an mRNA molecule and amino acids
32
Codons
- Three nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination signal
- The basic unit of the genetic code
33
DNA:
- contains information to direct all cell processes
| - deoxyribonucleic acid
34
DNA replication
- DNA Needs to be present in every cell
- Has to be copied before cell can divide
- To direct cell processes RNA has to be made from DNA
- RNA directs protein Synthesis (enzymes)
- Semi-conservative
o Part of the old DNA molecule becomes part of the new molecule
- Each base can only be paired with its complement: A:T, G:C
o Complement base pairing
- Many enzymes are involved but replication happens very quickly
35
Each chromosome contains information for
o The formation of proteins
| o Has many hundreds of genes
36
- Each proteins is “coded” for
o By a specific segment of the DNA molecule
37
Gene
- Segment/ discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA
- Located in its chromosomal DNA
38
Basic structure of DNA
```
- Double helix
o Two long strands twist around each other like a twisted ladder
- Made up of six smaller molecules
o Five carbon sugar – deoxyribose
o Phospahate molecule
o Four different nitrogenous bases
Adenine, thymine, cytosine, and guanine
- A, T, G, C
- Deoxyribose
- Nucleus to E.R
```
39
Basic structure of RNA
- Single stranded
- A, U, G, C
- Ribose
- Goes out of nucleus
40
Know how the information in genes gets transformed into proteins
- The information in the sequence of bases A,T,G,C has to be put into RNA before the RNA can be used to make proteins
41
Transcription
- DNA -> RNA
42
Translation
- RNA -> Protein
43
Know how changes in genes may affect the genetics of the organism
- Changes in genes causes mutation that affects genetics and may introduce new traits into an organism
44
Differentiation
o Specialization on the structure and function of cells that occurs during the development of an organism
o Results froom selective activation and deactivation of the cells genes
45
Mutations
o Change in the nucleotide sequence of an organisms DNA
o The ultimate source of genetic diversity
o Can occur in DNA or RNA of virus
46
Neoplastic
o A new, often uncontrolled growth of abnormal tissue; tumor
47
Oncogenes
o A cancer – causing gene
| o Usually contributes to malignancy by abnormally enhancing the amount or activity of a growth factor made by the cell
48
Recombinant DNA
- DNA molecule carrying nucleotide sequences derived from two or more sources
49
Nucleotide
- Building block of nucleic acids
| - Consisting of a five carbon sugar covalently bonded to a nitrogenous base an one or more phosphate group
50
Gene cloning
- Production of multiple copies of gene
51
Genetic Engineering
- Direct manipulation of genes for practical purposes
52
Gene therapy
- Treatment for a disease in which the patient’s defective gene is supplemented or altered
53
Plasmids
- Small ring of independently replicating DNA separate from the main chromosome
- Found in prokaryotes and yeasts
54
Restriction enzymes
- Bacterial enzyme that cuts up foreign DNA (at specific DNA sequences called restriction sites), thus protecting bacteria against intruding DNA from phages and other organisms
- Used in DNA technology to cu DNA molecules in reproducible ways
- Pieces of cut DNA are called restriction fragments
55
GMO
- Genetically modified organism
- Organism that has acquired one or more genes by artificial means
- From another species – transgenic organism
56
GMF
- Genetically modified Food
57
PCR
- Polymerase chain reaction
| - Technique used to obtain many copies of a DNA molecule or a specific part of a DNA molecule
58
What is an allele?
- Alternative version of a gene
59
What is a gene?
- Molecular unit of heredity of a living organism
- Consist of stretches of deoxyribonucleic acid (DNA) that code fro proteins that perform the necessary cellular functions in an organism
- Passed on to an organisms offspring so that its traits are inherited
60
What is the genetic code?
- Set of rules that dictates the correspondence between RNA codons in an mRNA molecule and amino acids in protein
61
Briefly describe the process of DNA replication.
- Part of the old DNA molecule becomes part of the new molecule
- Each base can only be paired with its complement: A,T and G,C
- Complement base pairing
- Many enzymes involved
62
Briefly describe what happens during transcription
- RNA synthesis
o RNA made using DNA as pattern
- RNA polymerase
- “reads” only one strand of the DNA : The sense Strand
- DNA put back together, left intact after transcription
63
Describe the process of translation.
- Synthesis of proteins/polypeptides using genetic information encoded in an mRNA molecule
64
How many different types of RNA are made by cells?
- Three major types of RNA
o mRNA
o rRNA
o tRNA
65
mRNA, rRNA, tRNA
- mRNA
o messenger RNA
o serves as temporary copies of the information found in DNA
- rRNA
o ribosomal RNA
o serve as structural components of protein-making structures known as ribosomes
- tRNA
o transfer RNA
o ferry amino acids to the ribosome to be assembled
66
Be able to describe and identify the differences between RNA and DNA.
```
Basic structure of DNA
- Double helix/stranded
o Two long strands twist around each other like a twisted ladder
A, T, G, C
- Deoxyribose
- Nucleus to E.R
Basic structure of RNA
- Single stranded
- A, U, G, C
- Ribose
- Goes out of nucleus
```
67
Where does replication take place?
Where does transcription take place?
- Nucleus
| - nucleus
68
Where does translation take place?
in the cytoplasm
69
What are ribosomes? What do they do?
- Cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm
70
If a DNA strand has the following sequence (AACGTA), what is the RNA sequence?
- UUGCAU
71
Every gene begins with what type of signal?
- Turning on/off gene???
72
What is differentiation? What is its result?
- Differentiation
o Process of cell specialization during development
- Result of differentiation
73
What is a mutation?
- Change in the nucleotide sequence of an organisms DNA
| - Ultimate source of genetic diversity
74
Describe the different types of mutations
- Point mutation
o Change in a single nucleotide substitutions
One base exchanged for another
May cause amino acid to change
- Frameshift mutation
o Deletions or substitutions cause the entire reading fame to be changed
Drastic changes result in aa sequence
75
What is the difference between a neoplastic cell and a cancerous cell?
no clue
76
What is a GMO?
Genetically modified Organism
77
The observed characteristics of an organism are called ?
- Gene
78
Genes that are on the X or Y chromosome are called?
- Autosomal gene
79
What is phenotype?
- The expressed trait of an organism
80
What is genotype?
- Genetic makeup of an organism
81
Describe the difference between dominant and recessive alleles?
- Dominant – show their effect even if the individual only as one copy of the allele – heterozygous
- Recessive only shows effect if the individual has two copies of the allele – homozygous
82
What does sex-linked mean?
- Gene located on a sex chromosome
| - In humans, the vast majority of sex-linked genes are located on the X chromosome
83
Incomplete dominance
- Type of inheritance in which the phenotype of a heterozygote Aa is intermediate between the phenotypes of the two types of homozygotes AA and aa
84
Co-dominance
- Inheritance pattern in which a heterozygote expresses the distinct trait of both alleles
85
Polygenic
- Inheritance – the additive effects of two or more gene loci on a single phenotypic characteristic
86
Interphase
- Period in eukaryotic cell cycle when the cell is not actually dividing
- Constitutes the majority of the time spent in the cell cycle
- Cell is engaged in metabolic activity and performing its prepare for mitosis
- chromosomes are not clearly discerned in the nucleus
- cell may contain pair of centrioles
87
• Proteins
RNA directs protein synthesis (enzymes)
o 1. Enzymes – all that function in biological systems are proteins
Every reaction has to be regulated by a particular enzyme otherwise reaction doesn’t take place
Mediate all cellular reactions
o 2. Structure
Protein are arranged differently that gives shape
Shape determined network of protein
88
o The only information that is house in DNA is to make _____ for RNA
o The only necessary thing for the cell know how to do is to make
Protein
89
DNA
```
Double-Stranded, chains of nucleotides
A T and G C are linked together
Twisted: Double helix (spring)
Nucleotides bind to each other
Complimentary Base Pairing
Strands ran in different direction – Anti Parallel
o 5 always link to phosphate carbon 3 prime always linked to OH group
o Everything else function with DNA
o (5 prime phosphate end – 3 prime Hydroxyl end)
Deoxyribonucleic Acid
o (sugar) 5 carbon sugar – pentose
Check notes
Twisted Rope ladder
```
90
REPLICATION
DNA replication is semi-conservative:
part of the old DNA molecule becomes part of the new molecule
- 1953 structure of DNA was not evident until then
- Duplication of DNA is referred to as Replication
- Semi-conservative – part of the oldDNA molecule shows up in each of the copies (2)
Each base can only be paired with its complement : A : T , G : C
Complement base pairing
- All base on base pairing
- Break up makes new strand (unzip) separate – hydrogen bond individual bases are easy to break
- One by one the empty spot is filled in with its complement A – T G- C
- End up with identical base pairs
- Until completely replaced rung by rung
- Happens only with enzymes
- Parent DNA Unzip missing nucleotides are bonded and have two identical daughter of molecules of DNA
o Exactly same DNA in two different cells
Many enzymes are involved but replication happens very quickly
91
-- All organism as a result of ____ but Bacteria
sexual reproduction
92
DNA STRUCTURE
Bacteria – DNA is wound around itself creates a Circle 0
o Only one piece of that DNA per cell
Prokaryotes
o DNA in linear pieces
Each piece is called a chromosome
Pack a lot of DNA in small package fit inside the nucleus inside the cell
Wrapped tightly around proteins known as histones
DNA – thousands of base pairs
o To duplicate chromosomes all same time (humans) in two directions – towards each other
o Replication forks run to each other and merge
o End up identical DNA
All replication process has to be coordinated in (eukary) – gets replicated in same time all DNA is ready to put together dividing all same time
93
CHROMOSOMES, DNA and GENES
Each chromosome contains information for the formation of proteins
Each protein is “coded” for by a specific segment of the DNA molecule
Each of these segments is called a GENE
Each chromosome has many hundreds of genes
94
human DNA
Humans 4 billion base pair along 43 chromosomes, all 4 billions must replicate everytime a cell divides
o Produce about 100,000 different proteins
Has to have a space on DNA this is the information to make that protein
We have amylase in our saliva
• Enzyme breaks down starch
• Made from salivary gland cell
This is pattern to make protein amylase (same all)
- Each chromosomes have many hundreds of Genes into
- To turn Gene into a protein information has to go through an intermediate
- Make RNA from DNA
95
What must happen before the RNA can be used to make proteins
The information in the sequence of bases (A,T,G,C) has to be put into RNA
Has to get transmitted into a sequence of amino acides in order to make proteins
Intermediate player is RNA
96
- RNA follows segment of
| - mRNA molecule produce
- whats in DNA molecule
| - series of amino acids
97
translation
| - RNA transcribed in the nucleus travels where to do what?
out of the nucleus into the cytoplasm to the rough E.R. to direct protein synthesis :
98
The sequence of DNA bases determines
the sequence of RNA bases.
99
Genetic Code
The sequence of DNA bases determines the sequence of RNA bases.
RNA bases, in groups of three, determine the sequence of amino acids put together during protein synthesis: translation
These groups of RNA bases (codons) and their corresponding amino acids are called the Genetic code
100
how DNA gets transmuted into action
```
Transcription
Translation
Linked together
Language of DNA, RNA of Protein
Transcribe into more recognizable symbol
```
101
Transcription
o DNA make RNA
o RNA synthesis
o Changing the alphabet from one to another
o Eukaryotic cells: happens in nucleus
o Often result: referred to as a Transcript (that which is transcribed)
o Leave nucleus goes to Rough Er then translated there
o RNA synthesis: RNA made using DNA as pattern
102
o RNA synthesis: RNA made using DNA as pattern
Whatever starting compound is, not destroyed but reused make it
RNA polymerase – able to decide which strand of DNA is message, which has got right sequence to it, read only one of those
“reads” only one strand of the DNA: the sense strand
DNA put back together, left intact after transcription
RNA polymerase: grabs into a piece of DNA and unzip a small portion of it and creates a bubble in the DNA molecule called the transcription bubble
103
RNA polymerase: grabs into a piece of DNA and unzip a small portion of it and creates a bubble in the DNA molecule called the transcription bubble
* Because they are separated they can be used to match complementary RNA basis on a one to one basis
* Basis paired are floating around cell as triphosphate nucleotide
* ATP, GTP, CTP, UTP – always have to have this in cell
* Anti-parallel ) how tells which strand it prescribe
* Only reads from 3’ prime to 5’ prime direction
* RNA is made in the 5’ to 3’
* Once grab to DNA can only travel to one direction; move along DNA molecule iin one direction depending upon which it grabs to
* Infront of everything it suppose to transcribe there is a sequence of DNA bases called PROMOTER
104
Translation
o Protein synthesis
o RNA to make protein
o Translate from Greek into English
o In cells language of nucleic acid to language of protein
105
Replication, transcription, translation
Make DNA from dna – replicatioin – DNA Synthesis
DNA make RNA – Transcription
Rna to make Proteins - translation
106
RNA
Lots of RNA there is in cell base on function
3 principle type
```
o 1. mRNA
“messenger”: code for a protein
Pattern that wil turn into a particular pattern
o 2. tRNA
Transfer RNA
Amino acids shuttle
o 3. rRNA
Ribosomal RNA
Forms part of ribosomes
o All different kids have to have a place in molecule where they are coded for
```
107
•who directs protein synthesis (enzymes)
RNA
108
Function of Nucleic acid
Replication
DNA -> RNA transcription
RNA -> protein translation
109
translation
RNA transcribed in the nucleus travels out of the nucleus into the cytoplasm to the rough E.R. to direct protein synthesis :
110
Transcription
* RNA synthesis : RNA made using DNA as pattern
* RNA polymerase
* “reads” only one strand of the DNA : the sense strand
* DNA put back together, left intact after transcription
111
RNA processing
* In eukaryotic cells, RNA is processed before leaving the nucleus
* RNA processing involves many different steps but the most important is the removal of unnecessary segments called introns
112
TRANSLATION
| Consists of three different processes:
* Initiation
* Elongation
* Termination
113
Components of Translation
* Ribosomes : proteins and rRNA
* mRNA : messenger RNA : holds the pattern for the protein
* tRNA : carries amino acids to the ribosome
* Amino acids : to be bound together in a polypeptide chain
114
Initiation
o Ribosome subunit binds to mRNA at the START sequence AUG which always code for methionine
o 1st amino acid in any protein is always methionine
o tRNA molecules bound to a specific amino acid is bound by the ribosome if sequence match up: codon to anticodon
codon on mRNA
anti codon on tRNA – other end is methionine
large subunit bound to small one bound to mRNA
tunnel around mRNA molecule
o in nucleus
115
Elongation
o The ribosome binds the second tRNA-amino acid in place
o Another 3 codons inside the Ribosome (big)
o Stable accumulation of molecule waiting for next molecule
o 2. If this configuration is stable ( all the right pieces) then the enzyme bind the 1st amino acid to the second one and the first tRNA leaves the ribosome
o The ribosome then moves down the mRNA to the next codon
Move by one codon – covering the next 3 basis
• 1st codon is not now held same tight bond so it floats away so we got tRNA that’s not bound to amino acid to be reused by another cell and put correct amino acid on it
o All happen in nucleus
116
Termination
o Complex reactions with many variations
o All involve nonsense codons which do no tcode for any amino acids
o Upon termination the ribosomal completely falls apart; releasing the polypeptide, ribosome subunits and mRNA
o In cytoplasm
o Will happen until ribosome gets to stop codon
Does not have complementary tRNA
Another called RELASE FACTOR binds with it
Release FACTOR – binds and makes everything fall apart –ribosome falls off – long protein released – mRNA still intact so it can be used again to do the same thing over again
o The end result of translation is a long chain of amino acids linked together; a polypeptide chain
117
•The end result of translation is
a long chain of amino acids linked together : a polypeptide chain.
118
Genetic code
DNA – transcribed into RNA – Genetic code base on relationship of Bases to amino acids base on groups of 3 (3 bases are going to get translated as a single amino acid) next three are going to get translated as a different amino acid
The relationship is what is referred to as Genetic Code
3 sequential basis – Codons A-U G-C G-C
119
mRNA Codons
```
AUG (start)
o Methionine
o Start signal
o Thts where protein synthesis starts/
o Where translation starts
UAA - stop
UGA- stop
UAG- stop
o Non-sense codons
o Translation is nonsence
o Stop signal
o Codon that says that were done
Translation is always preceded by transcription
mRNA – not stable, whole other enzyme that eats up mRNA
cell is making mRNA if needed that protein
```
120
Differentiation
o Permanent turning on and off special particular genes
o Only happens when cells divide
o Tied with cell division
One cell becoming two and two cell becoming four and so forth
o When cell division happens all of the DNA that is all of cells is all the same but within cell differentiation the cells may not do the same thing other cells do – Differential Gene Expression
o what’s responsible for different cell type
o Atleast under natural condition it cant go backward
121
Deferential gene expression
Offspring differing line than other offsprings – different set of genes that is active (check notes)
What is going on outside cell when it divides that it expresses different than other offspring cells – (environment)
Change in gnee expression affects cell shape, what cell produces how cell catabolizes, affects where cell will end up
122
o Stem Cells –
any cells that can become any type of cells
Lots of differentn kind
Embryonic – massive cells that we all start off as
Lots of different stages in which some kind of stem cell differentiate further
• Rbc and WBC – stem cell from bonemarrow
• Stem cells from bonemarrow
o Cant produce brain stem cell
o Produce different kind RBC and wbc
123
reason cell stuck in one line of development has to do with
how DNA is packaged
o Check pp
o Iin order for a particular DNA to piece of RNA to Protein – segment of DNA has to be unpackaged and strung out
o The packages of DNA RNA histones gets permanently packaged and get undone and therefore can never be transcribed – how gene permanently turned off
o If changes in histones happens – never able to be unpackaged thenthat part of DNA can never be transcribed – if change the way DNA is packaged
o If no transcriptioin – translation tdoesnt happen
o Alternative RNA splicing
124
Human Genome
o Need about 100,000 protein’ (need 100,000 gene, but only found 1/3)
o 4B base pairs
25-30000 genes
o How to get 100,000 protein from only 30,000 genes
o Alternative RNA splicing
All mRNA comes from same DNA
Eukaryotic cells
125
Control of gene expression (whether it produces protein or not) also occurs with
```
pp
o Breakdown of mRNA
o Initiation of translation
o Protein activation
o Protein breakdown
```
126
Multiple mechanism regulate gene expression in eukaryote see PP
o DNA unpacking – wrap around histones
o Transcription – other proteins and control mechanism
o RNA processing – splicing/ how make mRNa more or less active
o Flow through nuclear envelope
127
Regulated by ______ – translation/transcription
enzymes
128
Mutations
Process don’t quite go the way expected
Any change in DNA sequence
Changes in the sequence of bases of DNA
Causes changes in the RNA sequence only when they are transcribed
Causes changes in the codons
Cause changes in the amino acid sequence
129
Cause of Mutations
* Point mutations :
* Frameshift mutations :
* DNA base changes may or may not result in changes in the sequence of RNA
* Changes in RNA base sequences may or may not result in aa sequences
130
Point mutations :
• a change in a single nucleotide
| Substitutions : one base exchanged for another : may cause amino acid to change.
131
Frameshift mutations :
•deletions or substitutions cause the entire reading frame to be changed: drastic changes result in aa sequence.
132
Change in DNA – mutation – doesn’t represent change in protein (redundancy)
o Silent Mutation
No evidence that mutation is there
Permanently change
o Non-sense mutation
Introduces stop codone where it shouldn’t be
o Frameshift mutation
See evident evidence
Entire sequence is affected – one missing ribosome shifts read 3
o Miss sense mutation
Most evident
Sickle- celled anemia
• Changed in hgb (protein in RBC that carries o2)
• Ability to cary o2 depends on cell shalpe
• Single amino acid change
• Significantly change shape of molecule
• Changed RBC
• Curved RBC – not carry o2 as well, our body recognize as abnormal our own cleaning system get rid of it
• O2 not carried as well, not as many RBC to do it
• Tired lethargy
• Association who are indeginous to Africa where malaria is
• More resistant to malaria
• Mutation is an adaptation to surviving malaria
o Die before puberty – malaria – found in children younger than 5
o Survive long enough to reproduce
o Stayed in population the mutation
133
Causes of mutations
o Mistakes in replication or transcription (very rare)
Has way of fixing own mistakes
o Environmental influences to chemically change the base structure: radiation and mutagens
Industrial solvent
Radio activity
Acetone
X-rays
o Not all mutations are detrimental to the organism
o Mutations responsible for all the difference seen in related organisms
Slight Changes of DNA from one or another
134
Cancer results from
Mutation in genes that control cell division
Oncogenes
Tumor-suppressor genes
135
Neoplastic cells
• If left unchecked and create a mass of neoplastic cells
o Cancer
Some benign
• Tend to grow more slowly
Malignant
• Name: The way the cell invades other tissues
Progressions involves a lot of processes/ not predestined
• Produced in body all the time, but other body system have a way of dealing with them in normal condition
• Genetics of particular cells
Change from normal to a neoplastic cells
• Result of mutations that occur within normal genetic cells
136
Every cell has a gene name oncogene (cancer)
o Proto-oncogene in normal cells
o Have something to do with regulating cell cycle
o Highly regulated
137
Another cell – tumor-suppressing genes
```
o Normaly inhibits cell division
o Suppress the onco gene
Output of both genes is some kind of proteiins
o Both present in most cells
o Both have two each
```
138
Oncogenes
o If single copy (there are two copies of every gene)
o Can be turned on to proto to oncogenes
Number ways of proto-oncogenes to become oncogenes
o Promotes cancer when present in a single copy
o Check pp
o Some specific cases – theres a precise connection between virus infection / diseases to oncogenes
139
Tumor-supressor genses
o Both copies of tumor suppressor genes must be deactivated for cancer
o Check pp for graphics
o Two good copies produce protein help regulate cell division
o If defective, nonfunctioning protein, no inhibition- cell division not under control, neoplasticity
Must have both copies producing defective cells
140
Proto-oncogene DNA -> mutation within ghe gene -> oncogene
```
o Change of product – abnormal growth
o Same product – normal growth
In order to create neoplastic mutation both must occur – onco and tumor
Takes four or more to make it happen
```
141
Colorectal cancer
o Check pp
o Mutation into proto-oncogene – turns oncogene on
Producing some protein causing hyperactivity
Same time normal tumor suppressor gene – normal growth
Virus – disrupts tumor-supressor gene
• One – suppressor gene is still making one – still ok
• Two – fourth mutation – produce neoplastic cells
o Increased cell division -> growth of polyp -> growth of malignant tumor (carcinoma
o DNA changes: oncogene activated -> tumor-suppressor gene inactivated -> second tumor suppressor gene inactivated
o All cells are offspring of one or two set of cells that experience the first mutation
o We still have immune system cells that’s targeting cancerous cell – battle of time, how fast grow, or whether or not immune system can combat it
o Can have neoplastic cell that doesn’t destroy good cell – benign
Normal tissue function
o Some cases – tumor grows in such a way and outcompete and starts destroying good tissues – malignant
o Normal chromosomes – 1 mutation – 2 – 3 -4 (all four then we get malignant cell or neoplastic cell(not same)
142
o Malignant tumor
1. Virulence of cancer – dividing faster than normal cells
Destroying normal tissue function
2. Cells tend to have characteristics, specially if growing quickly, part of it can break off and go elsewhere in body
• Metastasis
o In of normal blood stream transfer
o End up with tumor in the liver
• Tumors can create their own circulations
o Induce body to create blood vessels
o Difficult to start, theres a bloodsupply
o Make body make new blood vessels
• Cause same
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Specific examples between virus can cause this type of mutation and specific type of cancer
o Herpes 8
Associated with Kaposis sarcoma
• Only happens in aids patient
• Reason: aids patient immune system is suppressed
• Inability of immune system to stop it
o EBV
Responsible for mononucleosis
In certain individuals – associated with Burkitt’s lymphoma
• Not inevitable
• Only see on some people who are west Afrikan descendants
o Hepatitis C
Connected with hepatocellular canceer (liver)
• Only happens in patient that already has cirrhosis of the liver
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Treatment of cancer
o Starting to use viruses as a vehicles to allow our own human system to attack cancer
Modified changed virus in order to give just the cancer a disease
• Disease not get rid of cancer, but highlights cancer for immune systems
• Hightens response of immune system
Because of genetic changes within virus itself, virus only going to attack the cancer not healthy cells
One of targeted cancer types is melanoma (skin cancer)
Using deadly virus (chicken fox, polio
• To introduce markers
o Problem of cancer and immune systemnot work
Our cells, immune doesn’t recognize the good and bad
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Genetics technology
Cloning, referred to as different terms
More often used is Biotechnology
Purposely changing genetics to produce a particulary product it normally wouldn’t
All base on idea that you can take dna and change it outside the cell
DNA recombination
Familiar with results not technique
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o Genetic engineering
Results of copying a gene is your able to take a single gene in a single cell and now lots of copies of genes in lots of cells
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o Recombinant DNA
Take from one kinds of DNA and take it to another (two organisms)
Gene carrier, vector
Dependent upon discovery of plasmid DNA and ability to mix and match plasmid DNA possible through endonuclease enzymes
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Plasmid DNA
• Small DNA not part of nucleus
• Extra pieces of DNA
• Most cells naturally have them
• A lot of bacteria – ability to resist ???
• Good part – separate plasma dna to genomic dna
• Able to cut through dna in such a way that we can insert a new piece of DNA into plasmid
o Cut with same enzymes
o Fit together like puzzle
• Take plasmid and put it in new cell
• Produces same gene products
• Take what we want/gene stick it to bacteria cell, b cell makes it
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Examples of recombinant DNA
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Penicillin extracted from fungus
• Small
• Put it in bacteria cells –
• Produces lots of penicillin
Indigo dye
• Comes out of plant
• Very toxic to make
Digitalis
• Not make anymore
• Heart beats stronger
• Type of plant
• Put in bacteria cells
o Insulin
Use to be pigs pancreas
Human gene was taken out put in bacteria
• B produce insulin
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• Polymerase Chain reaction (PCR)
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o Amplification technique
o Take one piece of DNA to 100,000 pieces of DNA
o Don’t have to understand how its done
o With long piecies and short pieces
o Dependent upon PCR – amplification
o Isn’t tied to reproductive cycle of
o Done in tubes 24 to 36 hours
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Living organisms reproduce by two methods (like offspring)
DNA mixing
Asexual reproduction
Offspring are identical to the original cell or organism
Involves inheritance of all genes from one parent
o Dna mixing – all show up
Sexual reproduction
Offspring are similar to parents, but show variations in traits
Involves inheritance of unique sets of genes from two parents
o Non-identical offspring (mix between parents)
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Roles of cell division
Cells arise only from preexisting cells
Cell division perpetuates life
Cell division is the reproduction of cells
Virchow’s principle states “Every cell from a cell”
Asexual reproduction
Reproduction of an entire single-celled organism
Identical to eachother
Growth of a multicellular organism
Result of asexual cellular reproduction
Growth from a fertilized egg into an adult
Repair and replacement of cells in an adult (skin, hair)
Why? Depend upon organism
- Single cell – only way
- Multi – has a lot of roles
Sexual reproduction
Sperm and egg production (ova and pollen production inplants)
o Male and female gametes
A sexual cell, whether ova or sperm in humans, ova and polen in plants
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CELL CYCLE: GROWTH and DIVISION
In order for cells to divide (increase in number) each cell has to have a complete set of all the chromosomes necessary for that species
The DNA has to be duplicated before the cell can divide
o Equally divided between offspring
- Asexual reproduction
o In order for cell to divide and be identical, everything that was on original has to be in offspring, has to have copy of everything – components
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CELL CYCLE: GROWTH and DIVISION
The life cycle of the cell consists of a metabolic phase : interphase
Followed by the cell division : mitosis
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Interphase
G1 : Organelle duplication; mitochondria, centrioles,etc.
S : DNA replication
G2 : protein production; enzymes made in preparation for cell division
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Cell dividing – mitosis
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o Division of a cell into two identical daughter cells
o Each has subphases
o 5 subphases
Prophase
Metaphase
Anaphase
Telophase
(Cytokenesis)
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Interphase – normal life of a cell
o Divided up into 3 subphases
o G1, S, G2 (G – growth, S – synthesis)
Checkpoints, control systems that regulates how cell will interact
As G1 – during process, cell – checklist complete then cell makes commitment to go forward, something missing cell gets stalled
Regulates due to looking at whats present in cell during a particular check point
• Not clear – stuck
• If satisfied then commited to go through all stuff until next checkpoint
• Set of check and balances inorder to go to next process
• Between check points the cell is a necessary progression
o G1: organelle duplication; mitochondria, centrioles, etc
o S:DNA replication
o G2: protein production; enzymes made in preparation for cell division
All the enzymes/protein the cell will need before cell divides
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Duplicated Chromosome
o Composed of two sister chromatide
Equal to two DNA pieces
Held together at some point along – centromere
Distinguish by letnght by where the length where centromere appears
• Centromere – always not in middle
• Chromosomes in S phase in this phase
• Once S phase finishes looks like that
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Eukaryotic chromosomes are composed of chromatin
- Chromatin = DNA + proteins
- To prepare for division, the chromatin becomes highly compact, and the chromosomes are visible with a microscope
- Early in the division process, chromosomes duplicate
o Each chromosome appears as two sister chromatids, containing identical DNA molecules
o Sister chromatids are joined at the centromere, a narrow region
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Cell division
| Once DNA has been duplicated
the daughter chromosomes stick together in pairs
Each one is called a sister chromatid
Two sister chromatids makes up a duplicated chromosome
o To two chromatid G1 – I S-II G2 – I I
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Mitosis
Chapter 8 drawings what phases looks like *****
| o Physical changes happens in cell visible in microscope
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Prophase
:
Nuclear membrane dissolves
Nucleus disappears
Chromosomes appear
Individual chromosomes
Separate inteties
Centrioles migrate to poles
Move around opposite ends of cells
Accumulations of protein strands / in a circle
• Occurs as pairs of strands perpendicular to each other
• Organizing structure for mitosis/ referee
start to form protein fibers between sets of centriole
Spindle begins to form
aster
(asters appear)
o Happens until centriole ends up in opposite site of cell and nuclear material disappears and chromosomes lined up in middle of cell
The equator of cell
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Metaphase
:
Chromosomes line up along middle of cell (equator)
Asters fully formed
o Splinders attqach to chromosomes – lined up side by side by side
o Once stabilized next happens
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Anaphase
: Chromosomes start to separate, moving toward the poles (asters)
o Spindle fibers shortens then pull the chromosomes pull apart from each other
Identical DNA to each other
Spindle ( proteins)
Most distinct visually
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Telophase
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:
Chromosomes reach the poles
The cleavage furrow becomes very prominent
Physical separation of two cells
Nuclear membrane begins to reappear
o The end (telo)
o Happen fairly rapidly
o Reform the nuclear membrane
o Starts of formation of separation between two cells
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Cytokinesis
The separation of the cells into two distinct cells
o The actual physical separation of distinct cells
o Center asters – center centrioles
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MITOSIS result and purpose
The purpose of mitosis is to produce new cells exactly like the ‘parent ‘ cells . The result of mitosis is two identical cells.
o Genetically identical cells
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MEIOSIS
To produce genetically diverse cells, the DNA of ‘parent’ cells has to be mixed. If all the DNA of both parents were mixed together then the offspring would have double the amount of DNA and this would change the offspring.
Therefore before sexual reproduction can take place, the chromosomes of each parent have to be reduced by half.
This reduction in the number of chromosomes is called MEIOSIS.
- Sexual reproduction – two cells has to fuse to produce offspring
- Every organism has set number of chromosomes
o H sapiens 46 chromosomes (23 each) (2N)
o Z Mays 20 (2N)
o Drosophila 8 (2N)
- Reduce number in some way inorder fertilization happens ends up in same number
o 8 + 8
4 pairs of chromosomes each
4 + 4 = 8
o How to get 4 pairs to 4 chromosomes
Meiosis – reduction of chromosomes by half
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Homologous chromosomes
* Chromosomes are similar
* Responsible for same type of information
* Two – look alike, same length, centromeres occurs in same place
* Mitosis – no distinction
* Chromosomes duplicate itself
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Meiosis I
o Prophase I
Organizing
Crossing over
• Homologous chromosomes – can exchange genetic information
o Same place in same type
o Centromeres in same place
o Switch
o Happens far from centromere in long chromosome than in short one
o Hasnt change function of chromosomes – same genes
Specific is different one half not identical to other half
o During metaphase I
Homogolous pair appears as group in middle of cell
o Anaphase 1
Homologous pairs separate from each other
o Telophase and cytokinses
No more diploid cell
Have haploid cell – 2 chromosomes
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Meiosis II
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o Prophase II
o Metaphase II
o Anaphase II
o Telophase II
o End up four haploid cells each with only 2 chromosomes
After meiosis H – 23 chromosomes
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Chromosomes
Chromosomes are matched in homologous pairs
Somatic cells have pairs of homologous chromosomes, receiving one member of each pair from each parent
Homologous chromosomes are matched in
Length
Centromere position
Gene locations
A locus (plural, loci) is the position of a gene
Different versions of a gene may be found at the same locus on maternal and paternal chromosomes
Chromosomes are matched in homologous pairs
The human sex chromosomes X and Y differ in size and genetic composition
Pairs of autosomes have the same size and genetic composition
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Meiosis
Meiosis is a process that converts diploid nuclei to haploid nuclei
Diploid cells have two homologous sets of chromosomes
Haploid cells have one set of chromosomes
- 4 haploid cells goes trhough developmental changes
o Become sex cells - gametes
Meiosis occurs in the sex organs, producing gametes—sperm and eggs
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Fertilization
Fertilization is the union of sperm and egg (gametes)
The zygote has a diploid chromosome number, one set from each parent
- Fusion of Gametes (haploid 1N) reulsts in a zygote
o Zygote (diploid 2N cell)
- In human development is not equal
o Result of meiosis 4 haploid cells
Male – all 4 develop into gametes
• Development continuous through out life of adult male
Females – of 4 haploid cells only 1 develops into gamete, rest degenerate and form covering for the egg
• Already there at birth
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review meiosis 1
Meiosis reduces the chromosome number from diploid to haploid
Like mitosis, meiosis is preceded by interphase
Chromosomes duplicate during the S phase
Unlike mitosis, meiosis has two divisions
During meiosis I, homologous chromosomes separate
The chromosome number is reduced by half
During meiosis II, sister chromatids separate
The chromosome number remains the same
Events in the nucleus during meiosis I
Meiosis reduces the chromosome number
from diploid to haploid
Prophase I
Chromosomes coil and become compact
Homologous chromosomes come together as pairs by synapsis
Each pair, with four chromatids, is called a tetrad
Nonsister chromatids exchange genetic material by crossing over
Metaphase I
Tetrads align at the cell equator
Anaphase I
Homologous pairs separate and move toward opposite poles of the cell
Telophase I
Duplicated chromosomes have reached the poles
A nuclear envelope forms around chromosomes in some species
Each nucleus has the haploid number of chromosomes
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Meiosis II
Meiosis II follows meiosis I without chromosome duplication
Each of the two haploid products enters meiosis II
Events in the nucleus during meiosis II
Prophase II
Chromosomes coil and become compact
Metaphase II
Duplicated chromosomes align at the cell equator
Anaphase II
Sister chromatids separate and chromosomes move toward opposite poles
Telophase II
Chromosomes have reached the poles of the cell
A nuclear envelope forms around each set of chromosomes
With cytokinesis, four haploid cells are produced
Meiosis reduces the chromosome number
from diploid to haploid
