Heredity & Societies Transmission Genetics (Lectures 4-6) Flashcards
Why did Mendel use peas?
Identifiable traits Easy to grow Take little space Inexpensive Short growth period Self fertilizing Artificially fertilized
Who is Johan Gregor Mendel
- monk
- expired mended peas to understand fundamental principles of genetics
What was mendle’s experimental design?
Large sample size over 10 yr period 7 different traits Repeated experiments Analyzed data with probability and statistics Lack of preconceived notion
Allele
Alternate form or variation of gene
2 types of alleles
Homozygous and heterozygous
Homozygous
Two identical alleles for a gene
Heterozygous
Two different alleles for a gene
Phenotype
Physical trait of an organism; obserable
Genotype
Genetic constitution of an organism
Dominant
The allele that the organism’s appearance
Recessive
alleles that has no noticeable effect on the appearance
Mendel’s first law
Principle of segregation
- members of a gene pair separate during the formation of gametes
- genes must separate during gametes formation so that each game contributes one gene to the zygote
Mendel’s Second Law
Principle of Independent Assortment: alleles of one pair of genes segregate into gametes independent of the alleles from another gene pair. Genes are packaged into gametes randomly
Mendelian inheritance in humans pigmentation gene and albinism
75% normals
25% albino
What is albinism
Pigmentation dominant and lack of pigment recessive 3:1 ratio
Where are autosomal traits located?
Human autosomal traits are located on the non sex chromosomes (1-22)
What are autosomal traits
They may be inherited as auto sales recessive or autosomal dominant. The non sex chromosomes
Pedigree
Depicts family relationships and patterns of inheritance for particular traits
Autosomal Recessive
- Unaffected parents have affected children
- All children of affected parents are affected
- Both parents Aa, risk affected child -25%
- Equal affected male and female
- consanguinity
Consanguinity
Kissing cousins
Autosomal recessive traits
- cystic fibrosis
- Tay sacks disease
- Sickle cell anemia
- albinism
- attached ear lobes
Autosomal Dominant
- requires one copy -mutant allele (Aa)- rarely (AA)
- aa: unaffected individuals
- affected individual- at least one affected parent
- Aa x aa: each child- 50%chance- affected
- Equal numbers- males and females two affected individuals -unaffected children
X Linked Recessive
- males: homozygous for genes on the X (doesn’t have an allied counter part)
- affected makes get faulty allele from mom- transmit to daughter but not son
- daughters of affected makes are heterozygous, thus unaffected
- for recessive traits, XX and XY affected
- more males affected
Autosomal dominant traits
- Marfan syndrome
- Ectrodactyly
- Neurofibromatosis
- Huntington disease
- Widow’s peak, freckles
X linked recessive traits
- hemophilia
- color blindness
- muscular dystrophy
Hemophilia
Blood does not clot, bleed to death
Royal disease
Color blindness
More male 1/12
Women 1/200
X linked dominant
Affected males- all affected daughter but no affected sons
Heterozygous females- unaffected and affected offspring;- equally affected
X linked dominant traits
Hypophosphatemia
And some types of hereditary hearing loss
Y linked
Passes only father to sons
Women never affected
Doesn’t skip generations
Y linked traits -rare-Y has fewer genes
Mitochondrial inheritance- non Mendelian inheritance
Mitochondria- have their own dna
- transmitted from mother to all of her offspring
- males and females equally affected
Who can pass down mitochondria
Mom
Polygenic traits/ disorders
Are determined by two or more genes -eye color
Multi factorial traits
Controlled by two or more genes and show significant interaction with the environment Height Skin Color Diabetes Obesity Cardiovascular Cancer
Twin studies
- Used often in studies to determine the influence of heredity and environment on the phenotype
- identical genes- if not identical in phenotype, may be deduced that environmental influences exists
- debate over nature vs nurture
What can the environment influence
The genotype to produce the phenotype
Risk factors for cardiovascular disease
Heredity Male Hypertension ldl (low density lipoproteins) or Hdl (high density lipoproteins) Smoking Obesity Lack of exercise Stress
Survey of multi factorial traits complex traits
Cardiovascular disease Diabetes Obesity Behavior Intelligence
Monozygotic twins
two offspring born of the same pregnancy and developed from a single fertilized ovum that splits into equal halves during an early cleavage phase in embryonic development, giving rise to separate fetuses
Dizygotic twins
two offspring born of the same pregnancy and developed from two ova that were released from the ovary simultaneously and fertilized at the same time.
Neural tube defects
A group of disorders that result from defects in the formation or development of the neural tube
Cystic fibrosis
damage to the lungs and digestive system.
Sickle cell anemia
loose oxygen. outside in the sun. common in African Americans,
hemizygous
Having only a single copy of a gene instead of the customary two copies.
muscular dystrophy
progressive weakness and loss of muscle mass. In muscular dystrophy, abnormal genes (mutations) interfere with the production of proteins needed to form healthy muscle.
Huntington disease
nerve cells in the brain. Huntington’s disease has a broad impact on a person’s functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders.30s or 40s
locus or loci
location of the gene/allele
genes
Carries of genetic information in the form of DNA
Marfan syndrome
weakness in connective tissue
Ectrodactyly
lobster claw syndrome
