Recombination:
Crossingoverandgametes
Prepare-se para as provas
Estude fácil! Tem muito documento disponível na Docsity
Ganhe pontos para baixar
Ganhe pontos ajudando outros esrudantes ou compre um plano Premium
Guias e Dicas
Prepare-se para as provas
Estude fácil! Tem muito documento disponível na Docsity
Encontrar documentos
Prepare-se para as provas com trabalhos de outros alunos como você, aqui na Docsity
Encontra documentos específicos para os exames da tua universidade
Encontra documentos específicos para os exames da tua universidade
Videoaulas
Prepare-se com as videoaulas e exercícios resolvidos criados a partir da grade da sua Universidade
Quiz
Responda perguntas de provas passadas e avalie sua preparação.
Ganhe pontos para baixar
Ganhe pontos ajudando outros esrudantes ou compre um plano Premium
Recombination in Genetics: Understanding the Shuffling of Alleles through Crossing Over, Notas de aula de Genética
An overview of recombination in genetics, focusing on the process of crossing over during meiosis. It explains how alleles are shuffled, resulting in recombinant and nonrecombinant gametes. The text also covers independent assortment and the importance of genetic markers in determining the recombinant or nonrecombinant status of gametes.
Tipologia: Notas de aula
2013
1 / 20
Esta página não é visível na pré-visualização
Não perca as partes importantes!
Documentos relacionados
Pré-visualização parcial do texto
Baixe Recombination in Genetics: Understanding the Shuffling of Alleles through Crossing Over e outras Notas de aula em PDF para Genética, somente na Docsity!
Recombination:
Crossing
over
and
gametes
Recombination!
Shuffling of alleles
Warning: Wikipedia definition is not precise - Fundamental to genetics and evolution -
A
gamete with a combination of alleles that did not come from the parents is a
recombinant
gamete
Examine by contrasting combinations of alleles at two stages: - Gametes that made person (from parents) - Gametes from person
Recombination!
Shuffling
of
alleles
X
cb
l
Parental
Nonrecombinant
X
ncb
L
X
cb
l
X
ncb
X
cb
Ll
Two
means
of
recombination
Independent
assortment
Process with different chromosomes
Crossing
over
Sometimes the word
recombination
is used specifically referring to crossing over
Wikipedia focuses just on this
Meiosis
but
it
isn
t
so
simple…
Often,
homologous
chromosomes
trade
pieces
with
each
other
during
meiosis
Happens when doubled
Called
crossing over
Can form mixed (
recombinant
chromosomes in gametes
What
are
we
working
with?
This
heterozygote
sometimes
experiences
crossing
over
during
meiosis
What
are
we
working
with?
This
heterozygote
then
passes
on
a
noncrossover
(nonrecombinant)
or
crossover
(recombinant)
chromosome
to
its
eggs
NR R R
How
do
we
tell?
We use look at alleles at genetic markers (discussed soon) along the chromosome!
Nonrecombinant
eggs:
A B ,
a b
Recombinant
eggs:
a B ,
A b
If
totally
linked
(no
recombination),
only
get
Nonrecombinant
eggs
Neighboring
gene
variants
(alleles)
tend
to
stay
associated
Start with heterozygote
Produces gametes, with crossover(s) occurring along the length - How often are A and B “ linked ” (ie, same color)? - How often are A and C “ linked ” ? - What does this mean?
If we assume total linkage
Imagine dad is
AABB
A B A B
Imagine mom is AaBb:
How
to
follow:
Ab^ aB
AB
AB
AABb^ AaBB
AABb^ AaBB
How
to
follow:
If we assume no linkage
Imagine dad is
AABB
A B A B
Imagine mom is AaBb:
Ab^ aB
AB
AB
AB^ ab
…
Phase
matters…
Recombinant gametes
AaBb Ab aB - AaBb
AB
ab Red chromosome came from this individual ’ s dad Blue chromosome came from this individual ’ s mom Punchline: Knowing an individual is “ AaBb ” is not enough to understand which gametes are recombinant vs. parental
Image
Credits,
Unit
Chromosomes, © Alexandr Mitiuc, all rights reserved, www.photoxpress.com