AP Biology Ch 12 gene linkage groups and chromosome mapsStephanie Beck
1. The document discusses linkage groups and chromosome mapping in genetics. It provides examples of crosses involving fruit flies that demonstrate genes located on the same chromosome tend to be inherited together, while genes on different chromosomes assort independently.
2. The document explains how observing recombinant vs parental offspring types allows geneticists to determine if genes are linked and calculate the distance between genes on a chromosome.
3. It provides practice problems demonstrating crosses to determine linkage and asks the reader questions about linkage and chromosome mapping concepts.
Modern cytogenetic tools in crop improvementShreyas A
it includes FISH, GISH and their recent modifications such as comparative genome hybridization, chromosome painting, spectral karyotyping, multicolour FISH, fiber FISH and Q-FISH
This power point presentation is designed to explain deviation of Mendelian dihybrid ratio due to interaction of genes which may be of following types
1.Two gene pairs affecting same character – 9:3:3:1
2.Epistasis, one gene hides effect of other
a) Recessive Epistasis - 9:3:4
b) Dominant epistasis - 12:3:1
3.Complementary genes - 9:7 ( 2 genes responsible for production of a particular phenotype )
4. Duplicate genes – 15:1 ( same effect given by either of two genes )
5. Polymeric gene action - 9:6:1
6. Inhibitory gene action - 13 : 3
Each interaction is typical in itself and ratios obtained are different
The document discusses how DNA is packaged in eukaryotic and prokaryotic cells. In eukaryotes, DNA is wrapped around histone proteins to form nucleosomes, which are further packaged into chromatin. Chromatin exists in a "beads on a string" structure. Additional non-histone proteins help package chromatin into higher-level structures. In prokaryotes, DNA is loosely organized into loops within the nucleoid region. Eukaryotic chromatin also exists in two forms - loosely packaged euchromatin and tightly packaged heterochromatin.
Mr. and Mrs. Snow have been trying for a baby but Mrs. Snow has suffered three miscarriages. Their family history also includes miscarriages. Genetic testing found that Mr. Snow has a balanced translocation that could be causing the recurrent miscarriages. The doctor refers them to a genetic counselor to discuss their test results and options for having a healthy pregnancy in the future.
This document discusses inheritance and provides examples of cytoplasmic inheritance. It describes Mendelian inheritance where genes located on chromosomes segregate in predictable ratios. Non-Mendelian inheritance involves genes located in the cytoplasm that are transmitted from the female parent only, with no segregation in F2 generations. Examples discussed include chloroplast inheritance in Mirabilis jalapa, kappa particles determining toxicity in Paramoecium, and shell coiling determined by cytoplasmic proteins in snails. Cytoplasmic male sterility is also summarized, where mitochondrial mutations cause pollen to be non-functional but are maternally inherited.
Gregor Johann Mendel (1822-1884) was an Augustinian monk and scientist who conducted breeding experiments with pea plants between 1856-1863. He cultivated and tested over 28,000 pea plants, finding that their offspring retained traits from their parents. Mendel's experiments led him to propose the laws of inheritance and hypothesize that traits are transmitted by "particles" (now known as genes). Although his work was largely ignored during his lifetime, it formed the foundation of modern genetics when it was rediscovered in 1900.
Inheritance due to genes located in cytoplasm is called cytoplasmic inheritance.
Since genes governing traits showing cytoplasmic inheritance are located outside the nucleus and in the cytoplasm, they are referred to as plasmagenes.
The concept of the gene has evolved over time based on experimental evidence:
1. Early views were that a gene equals one character (Mendel) or metabolic function (Garrod).
2. Experiments in the 1940s-50s showed genes encode enzymes or polypeptides.
3. Benzer's experiments in the 1950s-60s demonstrated that genes have fine structure and recombination can occur within genes, not just between genes. The nucleotide, not the gene, is the basic unit of genetic structure.
4. Complementation tests show a gene is the basic unit of function, though it can be divided into smaller functional units (cistrons). Alternative splicing further complicates the
Pertemuan 2. history of genetics Bu Rani WulandariSuryati Purba
1. The document discusses the history and key discoveries in genetics, including Mendel's work on inheritance in pea plants in the mid-1800s.
2. Major milestones include discoveries about DNA as the genetic material in the mid-1900s, and the sequencing of the human genome in 2001.
3. Genetics has advanced our understanding of heredity and molecular processes through analyzing mutants, mapping genes, and determining gene products and regulation.
This document discusses several principles of inheritance:
1) Mendel's laws of segregation, independent assortment, and dominance.
2) Codominance and incomplete dominance where both alleles are expressed in heterozygotes.
3) Multiple alleles where a single gene can have more than two forms.
4) Gene interactions and how Morgan's work with fruit flies demonstrated chromosomes contain genes and determine sex inheritance.
5) Extrachromosomal inheritance where traits are inherited through organelle DNA rather than chromosomes.
1. Mendel's experiments with pea plants in 1865 established the basic principles of genetics, including that traits are passed from parents to offspring through discrete units (now known as genes).
2. DNA was identified as the genetic material through experiments in the mid-20th century. DNA is made up of nucleotides with a sugar-phosphate backbone and nitrogenous bases that bond together in base pairs.
3. Genes provide instructions for making proteins through DNA transcription and translation of mRNA into amino acid chains, allowing cells to carry out their functions. The genetic code is universal across all life on Earth.
This document discusses various strategies for identifying disease genes, including position-dependent and position-independent approaches. Position-independent strategies include identifying a disease gene through knowledge of the protein product, using an animal model of the disease, or DNA sequence knowledge. Positional cloning involves mapping a disease to a chromosomal region and then identifying candidate genes within that region. Techniques like SSCP analysis and heteroduplex analysis are used to identify mutations in candidate genes. The candidate gene approach starts with a known or suspected protein involved in a disease.
1. Cytoplasmic inheritance involves the transmission of traits controlled by DNA in organelles like mitochondria and chloroplasts from the maternal parent alone.
2. Early studies showed that traits like shell coiling in snails are determined by the mother's genes, not the individual's own genes.
3. Sonneborn described the inheritance of cytoplasmic particles called "kappa" in Paramecium and their interaction with nuclear genes.
AP Biology Ch 12 gene linkage groups and chromosome mapsStephanie Beck
1. The document discusses linkage groups and chromosome mapping in genetics. It provides examples of crosses involving fruit flies that demonstrate genes located on the same chromosome tend to be inherited together, while genes on different chromosomes assort independently.
2. The document explains how observing recombinant vs parental offspring types allows geneticists to determine if genes are linked and calculate the distance between genes on a chromosome.
3. It provides practice problems demonstrating crosses to determine linkage and asks the reader questions about linkage and chromosome mapping concepts.
Modern cytogenetic tools in crop improvementShreyas A
it includes FISH, GISH and their recent modifications such as comparative genome hybridization, chromosome painting, spectral karyotyping, multicolour FISH, fiber FISH and Q-FISH
This power point presentation is designed to explain deviation of Mendelian dihybrid ratio due to interaction of genes which may be of following types
1.Two gene pairs affecting same character – 9:3:3:1
2.Epistasis, one gene hides effect of other
a) Recessive Epistasis - 9:3:4
b) Dominant epistasis - 12:3:1
3.Complementary genes - 9:7 ( 2 genes responsible for production of a particular phenotype )
4. Duplicate genes – 15:1 ( same effect given by either of two genes )
5. Polymeric gene action - 9:6:1
6. Inhibitory gene action - 13 : 3
Each interaction is typical in itself and ratios obtained are different
The document discusses how DNA is packaged in eukaryotic and prokaryotic cells. In eukaryotes, DNA is wrapped around histone proteins to form nucleosomes, which are further packaged into chromatin. Chromatin exists in a "beads on a string" structure. Additional non-histone proteins help package chromatin into higher-level structures. In prokaryotes, DNA is loosely organized into loops within the nucleoid region. Eukaryotic chromatin also exists in two forms - loosely packaged euchromatin and tightly packaged heterochromatin.
Mr. and Mrs. Snow have been trying for a baby but Mrs. Snow has suffered three miscarriages. Their family history also includes miscarriages. Genetic testing found that Mr. Snow has a balanced translocation that could be causing the recurrent miscarriages. The doctor refers them to a genetic counselor to discuss their test results and options for having a healthy pregnancy in the future.
This document discusses inheritance and provides examples of cytoplasmic inheritance. It describes Mendelian inheritance where genes located on chromosomes segregate in predictable ratios. Non-Mendelian inheritance involves genes located in the cytoplasm that are transmitted from the female parent only, with no segregation in F2 generations. Examples discussed include chloroplast inheritance in Mirabilis jalapa, kappa particles determining toxicity in Paramoecium, and shell coiling determined by cytoplasmic proteins in snails. Cytoplasmic male sterility is also summarized, where mitochondrial mutations cause pollen to be non-functional but are maternally inherited.
Gregor Johann Mendel (1822-1884) was an Augustinian monk and scientist who conducted breeding experiments with pea plants between 1856-1863. He cultivated and tested over 28,000 pea plants, finding that their offspring retained traits from their parents. Mendel's experiments led him to propose the laws of inheritance and hypothesize that traits are transmitted by "particles" (now known as genes). Although his work was largely ignored during his lifetime, it formed the foundation of modern genetics when it was rediscovered in 1900.
Inheritance due to genes located in cytoplasm is called cytoplasmic inheritance.
Since genes governing traits showing cytoplasmic inheritance are located outside the nucleus and in the cytoplasm, they are referred to as plasmagenes.
The concept of the gene has evolved over time based on experimental evidence:
1. Early views were that a gene equals one character (Mendel) or metabolic function (Garrod).
2. Experiments in the 1940s-50s showed genes encode enzymes or polypeptides.
3. Benzer's experiments in the 1950s-60s demonstrated that genes have fine structure and recombination can occur within genes, not just between genes. The nucleotide, not the gene, is the basic unit of genetic structure.
4. Complementation tests show a gene is the basic unit of function, though it can be divided into smaller functional units (cistrons). Alternative splicing further complicates the
Pertemuan 2. history of genetics Bu Rani WulandariSuryati Purba
1. The document discusses the history and key discoveries in genetics, including Mendel's work on inheritance in pea plants in the mid-1800s.
2. Major milestones include discoveries about DNA as the genetic material in the mid-1900s, and the sequencing of the human genome in 2001.
3. Genetics has advanced our understanding of heredity and molecular processes through analyzing mutants, mapping genes, and determining gene products and regulation.
This document discusses several principles of inheritance:
1) Mendel's laws of segregation, independent assortment, and dominance.
2) Codominance and incomplete dominance where both alleles are expressed in heterozygotes.
3) Multiple alleles where a single gene can have more than two forms.
4) Gene interactions and how Morgan's work with fruit flies demonstrated chromosomes contain genes and determine sex inheritance.
5) Extrachromosomal inheritance where traits are inherited through organelle DNA rather than chromosomes.
1. Mendel's experiments with pea plants in 1865 established the basic principles of genetics, including that traits are passed from parents to offspring through discrete units (now known as genes).
2. DNA was identified as the genetic material through experiments in the mid-20th century. DNA is made up of nucleotides with a sugar-phosphate backbone and nitrogenous bases that bond together in base pairs.
3. Genes provide instructions for making proteins through DNA transcription and translation of mRNA into amino acid chains, allowing cells to carry out their functions. The genetic code is universal across all life on Earth.
This document discusses various strategies for identifying disease genes, including position-dependent and position-independent approaches. Position-independent strategies include identifying a disease gene through knowledge of the protein product, using an animal model of the disease, or DNA sequence knowledge. Positional cloning involves mapping a disease to a chromosomal region and then identifying candidate genes within that region. Techniques like SSCP analysis and heteroduplex analysis are used to identify mutations in candidate genes. The candidate gene approach starts with a known or suspected protein involved in a disease.
1. Cytoplasmic inheritance involves the transmission of traits controlled by DNA in organelles like mitochondria and chloroplasts from the maternal parent alone.
2. Early studies showed that traits like shell coiling in snails are determined by the mother's genes, not the individual's own genes.
3. Sonneborn described the inheritance of cytoplasmic particles called "kappa" in Paramecium and their interaction with nuclear genes.
1. The document compares genetic and linguistic diversity in Europe and finds some correlations between the two.
2. Structural features of languages may provide a better basis for comparison than vocabulary. Principal component analysis of genetic and linguistic data show some similarities in clustering.
3. Recent population mixing can account for some inconsistencies between the genetic and linguistic patterns. Overall, geography, genetics, and language are interrelated but influenced by separate evolutionary processes over long time periods.
1. The document discusses three main questions regarding human evolutionary genetics: the debate between hybridization models vs. the Southern dispersal route out of Africa, the coevolution of cultural and biological diversity, and challenges to the persistence of racial paradigms given genomic data.
2. Regarding the first question, the author notes several problems with hybridization hypotheses and presents evidence supporting an earlier dispersal of modern humans out of Africa via a Southern route, avoiding contact with Neanderthals.
3. For the second question, the author reviews evidence that increases in brain size did not necessarily correlate with genes associated with cognitive functions, and that cultural and linguistic changes likely evolved in parallel with biological changes.
4.
Perché alle Olimpiadi le gare di sprint le vincono sempre atleti caraibici, le maratone gli africani dell'est, che però nel nuoto non combinano niente? Non sarà che ci sono differenze razziali? La risposta, ancora una volta, è no.
2. Domande 13.
• Quanti alleli diversi può avere un gene?
• Ci sono solo alleli dominanti e recessivi, o sono possibili
altre relazioni fra gli alleli dello stesso gene?
•Qual è l’effetto di una mutazione in un gene essenziale
per una funzione della cellula o dell’organismo?
• In che modo gli alleli di un locus possono modificare
l’espressione fenotipica degli alleli di altri loci?
3. Gli alleli dello stesso gene differiscono per le mutazioni che
portano. Possono essere molti, ma ogni diploide ne porta solo
due nel proprio corredo genetico
12. Match probability: qual è la probabilità che due individui
abbiano per caso lo stesso genotipo?
N di alleli P
2 0.375
3 0.185
4 0.109
5 0.072
6 0.051
10 0.019
Se gli alleli hanno tutti la stessa frequenza:
Con 2 alleli: P(AA)= 0.52
= 0.25; P(Aa)= 2 x 0.5 x 0.5 = 0.5; P(aa)= 0.52
= 0.25
P (AA,AA)= 0.252
= 0.0625; P(Aa,Aa)= 0.52
= 0.25; P(aa,aa)= 0.252
= 0.0625
match probability: = 0.0625 + 0.25 + 0.0625 = 0.375
13. Match probability: qual è la probabilità che due individui
abbiano per caso lo stesso genotipo?
Allele (ripetizioni) Freq.
12 0.015
13 0.015
14 0.134
15 0.290
16 0.229
17 0.162
18 0.162
Con il solo D3S1358, in bianchi americani
P = 0.071
14. Match probability: qual è la probabilità che due individui
abbiano per caso lo stesso genotipo?
Con più loci come D3S1358:
N geni P e cioè
5 0.0715
1 su 560 mila
10 0.07110
1 su 318 miliardi
13 0.07113
1 su 900 000 miliardi
La popolazione terrestre è di circa 7 miliardi di individui
13 loci bastano e avanzano
15. E quindi
I loci STR nel nostro DNA ci dicono:
1. Se il materiale biologico ritrovato sul luogo di un crimine proviene da
un certo sospetto, e che probabilità c’è di sbagliarsi
2. Se un certo signore può essere il padre di un certo bambino, e che
probabilità c’è di sbagliarsi
3. Se un corpo non identificato può appartenere a un individuo con un
certo grado di parentela con certi altri, e che probabilità c’è di
sbagliarsi
Inoltre, lo studio di loci STR in altri genomi ci permette di:
4. Identificare specie protette e combattere il bracconaggio e il commercio
illegale
5. Individuare batteri e altri microorganismi che inquinano suolo, acqua e aria
6. Eccetera
22. Pelliccia gialla nel topo
Non si riescono a ottenere linee pure a pelliccia gialla
giallo X selvatico giallo X giallo
1 giallo : 1 selvatico 2 giallo : 1 selvatico
Come mai?
25. Penetranza ed espressività sono
due modi per definire l’effetto
dell’ambiente e di altri geni sui
caratteri ereditari
Fra i fattori che possono risentirne:
età di insorgenza delle patologie,
gravità dei sintomi, associazione ad
altri sintomi, risposta al
trattamento farmacologico
Penetranza incompleta ed espressività variabile
31. Epistasi o interazione genica
La dominanza è una forma di interazione genica: fra due
alleli dello stesso gene
Interazioni più complesse avvengono fra geni diversi
Se c’è dominanza, i rapporti fenotipici in F2 1:2:1 diventano
3:1
Analogamente, molte interazioni geniche semplificano i
rapporti mendeliani
36. Placche laterali, ma
non struttura pelvica
Struttura pelvica, ma
non placche laterali
Né placche laterali, né
struttura pelvica
Placche laterali e
struttura pelvica
Due geni epistatici controllano la formazione dell’armatura ossea nello
stickleback
42. Epistasi: Forma del frutto in Capsella bursa pastoris
15:1
P: frutto a cuore x frutto allungato
F1: tutti a frutto a cuore
F2: 15 frutto a cuore : 1 frutto allungato
Due loci coinvolti.
A - - - oppure - - B - aabb
45. 1. Gene black (cr. 16). Determina se viene prodotto il pigmento
nero eumelanina, che poi può essere modificato da altri geni in
sfumature di rosso.
b b B −
46. 2. Gene agouti (cr. 24). Determina la distribzione di eumelanina e
feomelanina, cioè se il pelo ha colorazione compatta o sfumata. Almeno
5 alleli
AS
− aw
aw
47. 3. Gene extension (cr. 20). Determina la distribuzione dei prodotti
del gene A, se su tutto il corpo o solo in alcune aree. Almeno 4 alleli
E − ebr
ebr
48. S −
sp
sp
si
si
sw
sw
4. Gene spotting (cr. 20) o MITF (microphtalmia-associated
transcription factor). Determina la presenza e la quantità di macchie. Almeno
4 alleli
49. Razza Genotipi omozigoti comuni
Basset Hound BB EE
Beagle as
as
BB sp
sp
English bulldog BB
Collie BB EE
Dalmata As
As
BB sw
sw
Doberman at
at
EE SS
Pastore tedesco BB SS
Golden retriever As
As
BB SS
Levriero BB
Irish setter BB ee SS
Labrador retriever As
As
SS
Barboncino SS
Rottweiler at
at
BB EE SS
San Bernardo at
at
BB
Ogni razza di cane è omozigote per alcuni alleli
50. Dalmata: AS
AS
E E sw
sw
(Pigmento nero compatto, espresso su tutto il corpo, predominanza di bianco)
53. A locus -
Ay
- sable
aw
- agouti/wolf grey
at
- tan points
a - recessive black
B locus -
B - non-liver
b (bc
/bd
/bs
) - liver
D locus -
D - no dilution
d - dilution of eumelanin to blue or isabella
dl
- dilution plus colour dilution alopecia (hair loss)
E locus -
Em
- black mask
Eg
- grizzle/domino
Eh
- Cocker sable
E - normal extension (no mask)
e - recessive red
G locus -
G - greying
g - no greying
H locus -
H - harlequin
h - non-harlequin
I locus -
Alleles unknown
K locus -
K - solid black
kbr
- brindle
k - non-solid black
M locus -
M - merle
m - non-merle
S locus -
S - no white spotting
sp
- piebald
si
- irish spotting (may not be on S
locus)
T locus -
T - ticking
Tr
- roan
t - no ticking
Ma non finisce qui
54. Perché è così difficile definire le basi genetiche del diabete?
Diabete: un gruppo di disturbi metabolici accomunati dal fatto di presentare una
persistente instabilità del livello glicemico del sangue
55. Perché è così difficile definire le basi genetiche del diabete?
Diabete di tipo I
56. Sintesi 12
• Allelia multipla
• Dominanza intermedia
• Letalità
• Penetranza incompleta
• Espressività variabile
• Complementazione
• Epistasi
Un esempio: la colorazione della pelliccia dei cani
Dogs representing the phenotypes caused by the 4 alleles postulated by Little (1957). Top left: S allele—solid German Longhaired Pointer. Top right: si—Shetland Sheepdog with Irish spotting. Bottom left: sp—piebald spotted Cocker Spaniel. Bottom right: sw—Japanese Chin with extreme white spotting.