Ôn tập sinh học tdl121 gen 03 principles of heredity v2

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Principles of heredity

Materials were extracted from
Hartwell et al., 2018. Genetics: from genes to genomes, 6th edition and
Pierce, 2012. Genetics: a conceptual approach, 4th edition
unless cited otherwise
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Content
• Mendel’s laws of heredity
• Extensions to Mendel’s laws
• Sex determination and sex-related characteristics
• Linkage, recombination and gene mapping

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Content
• Mendel’s laws of heredity
• Extensions to Mendel’s laws
• Sex determination and sex-related characteristics
• Linkage, recombination and gene mapping

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The puzzle of inheritance
• People domesticated plants and animals, selected
and created many breeds but did not know
• What is inherited?
• How is it inherited?

• What is the role of chance in heredity?

• Misconceptions
• The homunculus: one parent contributes most to
an offspring’s inherited features
• Blended inheritance: traits become mixed and
forever changed in the offspring
Hartwell et al., 2018

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Discoverers of Mendel’s laws

Hartwell et al., 2018

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Mendel’s garden and microscope

Hartwell et al., 2018

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Factors contributed to Mendel’s success
• The garden pea Pisum sativum

Hartwell et al., 2018

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The garden pea (Pisum sativum)

• Bisexual flowers, self-fertilizing: pure breed Lưỡng tính, tự thụ: dịng thuần
• Feasible cross-fertilization: hybrid
• Generating many seeds: statistical analysis

Hartwell et al., 2018

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Factors contributed to Mendel’s success
• The garden pea Pisum sativum
• Discrete trait with antagonistic forms

Hartwell et al., 2018

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Studied traits with antagonistic forms

Hartwell et al., 2018

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Factors contributed to Mendel’s success
• The garden pea Pisum sativum
• Discrete trait with antagonistic forms

• Pure-breeding lines

Lai các dịng thuần

• Carefully controlled crosses, reciprocal crosses
• Numerical analysis of large numbers of plants and seeds

• Mendel was a brilliant practical experimentalist

Hartwell et al., 2018

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Dominant phenotype

Phenotype expressed by heterozygotes and identical to only one of

the homozygotes
Kiểu hình dị hợp tử, giống với chỉ một kiểu hình đồng hợp tử Hartwell et al., 2018
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Quy luật phân ly

The law of segregation

Hartwell et al., 2018

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Yellow F2 peas are either pure breeding or hybrid

Hartwell et al., 2018

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Phép lai phân tích

The testcross

Hartwell et al., 2018

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The testcross

Hartwell et al., 2018

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Quy luật phân ly độc lập

The law of independent assortment

Hartwell et al., 2018

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Molecular basis of seed shape trait

Sbe1: Starch-branching enzyme 1

Hartwell et al., 2018

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Molecular basis of seed color trait

Sgr: Stay green

Hartwell et al., 2018

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Mendelian inheritance in humans
• Most common and obvious human phenotypes arise from the
interaction of many genes
• Roughly 6000 single-gene traits known in humans as of 2016

• Genetic diagnosis

Hartwell et al., 2018

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Some of the most common single-gene traits in humans

Hartwell et al., 2018

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Pedigrees aid the study of hereditary traits in humans

Hartwell et al., 2018

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Cystic fibrosis

Hartwell et al., 2018

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Kiểu hình trội vs kiểu hình lặn

Dominant trait versus recessive trait

Di truyền thẳng
Cả bố và mẹ bị bệnh có
thể sinh ra con khơng bị
bệnh, nếu cả bố mẹ đều
mang KG dị hợp tử.

Cả bố và mẹ bị bệnh luôn
sinh ra con bị bệnh.
Di truyền ngang

Hartwell et al., 2018

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Content
• Mendel’s laws of heredity
• Extensions to Mendel’s laws

• Sex determination and sex-related characteristics
• Linkage, recombination and gene mapping

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Mendel’s laws are only for
• Single-gene trait

Tính trạng đơn gen

• Complete dominance Trội hồn tồn
• Genes on different chromosomes Gen nằm trên NST khác nhau

Hartwell et al., 2018

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Mở rộng của quy luật Menden

Extensions to Mendel’s laws
• Single-gene traits

• Two-gene traits

• Incomplete dominance

• Codominance
• Multi-allele gene
• Pleiotropy

Trội khơng
hồn tồn
• Additive

Đồng trội

• Recessive epistasis

Gen nhiều alen • Dominant epistasis

Gen đa hiệu

• Redundancy

• Multifactorial traits
• Penetrance and expressivity
• Quantitative traits

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Incomplete dominance

Snapdragons Antirrhinum majus

Heterozygotes differ from both homozygotes

Dị hợp tử khác với đồng hợp tử
Hartwell et al., 2018

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A possible explanation for incomplete dominance

Hartwell et al., 2018

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Codominance

Heterozygotes resemble both homozygotes

Hartwell et al., 2018

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Human ABO blood group antigens

A3GALNT, 9q34.2

Lodish et al., 2016

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Human ABO blood groups
Genotype

Antigens on
RBCs

Serum antibodies Blood group

Can receive
blood types

IAIA, IAi

A

Anti-B

A

A, O

IBIB, IBi

B

Anti-A

B

B, O

A and B

None

AB

AB, A, B, O

O

Anti-B and Anti-A

O

O

IAIB
ii

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Lentil seed coat patterns

Hartwell et al., 2018

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House mouse (Mus musculus) coat colors

Hartwell et al., 2018

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Pleiotropy

Ay is a dominant yellow allele
Ay is a recessive lethal allele
Hartwell et al., 2018

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Pleiotropy of sickle-cell anemia
Hartwell et al., 2018

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Extensions to Mendel’s laws
• Single-gene traits

• Two-gene traits

Hai gen quy định một tính
trạng

• Incomplete dominance

• Additive Cộng gộp

• Codominance

• Recessive epistasis Át chế gen lặn

• Multi-allele gene

• Dominant epistasis Át chế trội

• Pleiotropy

• Redundancy

• Multifactorial traits
• Penetrance and expressivity
• Quantitative traits

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Additive interaction

Hartwell et al., 2018

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A biochemical explanation for seed colors

Hartwell et al., 2018

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Recessive epistasis determines Labrador retriever coat color

Labrador retrievers
Hartwell et al., 2018

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A biochemical explanation for coat color

Hartwell et al., 2018

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Formation of A or B antigent depends on the H locus

FUT1, 19q13.3
Fucosyltransferase

Serum antibodies
against A, B and H
antigents
Pierce, 2012

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Bombay phenotype

Hartwell et al., 2018

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Reciprocal recessive epistasis determines flower color

Sweet peas (Lathyrus odoratus)

Hartwell et al., 2018

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A biochemical explanation

Hartwell et al., 2018

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Complementation test

Hartwell et al., 2018

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Dominant epistasis determines summer squash fruit color

Hartwell et al., 2018

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A possible biochemical explanation

Hartwell et al., 2018

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Dominant epistasis determines chicken feather color

Hartwell et al., 2018

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A biochemical explanation

Hartwell et al., 2018

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