Basic Genetics Flashcards by Iseoluwa Ojo

_____ are the basic units of heredity

Genes

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Each gene occupies a ______________ locus

fixed chromosomal

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A _____ is a section of a long ____ molecule, carrying information for the ___________

gene; DNA

construction of a protein.

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protein products of genes have a specific effect on the phenotype
T/F

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Gene products influence or determine traits such as _____,______

blood type, skin colour

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An allele is one of the many forms of a given gene

T/F

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Genes, are carried by _______.

chromosomes

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Traits- any detectable _______ characteristic of an individual; Also refers to the _____ characteristics of an individual i.e. traits such as height, eye color and blood type.

phenotypic; inherited

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Phenotype- observed _____,_______, or __________characteristics (determined by his ______ and _______ )

physical, physiologic, or biochemical

genotype and environment

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Allele- one of two or more _________, may arise as a result of _____

Mutation- A mutation is a ______ change in DNA structure

Locus- the ________ of a gene on a chromosome

Homozygous- having ______ alleles at a given chromosomal locus specifying a particular trait

Heterozygous- having a pair of _________ alleles at a given chromosomal locus

variants of a given gene; mutation

permanent; unique position

identical; non-identical

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Haplo-sufficiency: One functioning allele ___________

Haplo-insufficiency: One normal allele ______________

provides enough protein for normal function.

cannot provide enough protein for normal function.

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Acrocentric chromosome have satellite

T/F

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Acrocentric chromosome

A chromosome in which the ___________________

centromere is very close to one end.

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A submetacentric chromosome is a chromosome ___________________________

whose centromere is located near the middle

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A chromosome with equal chromosomal arms is termed _______ chromosome.

metacentric

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The complete collection of an organisms genetic material is called a ________

Genome

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the total set of different chromosomal DNA molecules in a cell doesn’t include mitochondrial DNA

T/F

It does

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The construction of a human was previously estimated to require ______ to ______ genes, however the HGP has revealed that only _______-______ genes is required (about the same as that of a _______ plant with ______ genes!!).

100,000 to 150,000

20,000 – 25,000

Mustard plant

26,000

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Lifetime frequency of genetic disease in a population is about ___ per 1000

____% of first trimester abortuses have chromosomal abnormalities

By the _____th year of life 5% of the population would have developed a disease with a significant genetic component

670

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Genetic disease results from ________

Every individual has about ___-__ mutant
genes

mutations

5-8

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Classification:
1.____ mutations

2.______ mutations

3.______ mutations

Gene

Genome

Chromosomal

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Classification of Genetic Disorders

Classical
 Mendelian disorders – ______ mutation of ____ effect
 Multifactorial Disorders – _______ mutation of ____ effect

Cytogenetic disorders

_______ mutations
 _______ mutations

single gene ; large

multiple genes ; small

Chromosomal

Genomic

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Gene Mutations

Are microscopic mutations

T/F

submicroscopic

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Gene mutations

Include:
1. _______
2.______
3. ________

Point mutations

Insertion

Deletion

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Gene mutation Include: 1. Point mutations- _____________ 2. Insertion- of ________________ 3. Deletion- of _____________ -2 & 3 are _______ mutations

substitution of a single nucleotide base by another base 1 or more base pairs into DNA 1 or more base pairs from DNA frameshift

Consequences of Gene Mutations • Alter the meaning of the genetic code- ______ _______ _______ •Failure of _______ •Production of abnormal proteins resulting in ______ of function e.g. abnormal ____ in osteogenesis imperfecta ______ of function e.g. ______ repeats in Huntington's disease produce neurotoxic protein

Missense mutation Nonsense mutation Frameshift mutation transcription Loss ; collagen Gain; trinucleotide

Chromosomal Mutations Rearrangement of genetic material leading to ___________ in the chromosome

visible structural changes

Chromosomal Mutations  Includes: 1. ________ 2. _______ formation 3. _________ 4. _______ 5.____________ formation

Translocations Isochromosome Deletions Inversions Ring chromosome

Genomic Mutations Loss or gain of _______ resulting in ___________________

whole chromosomes monosomy or trisomy (Aneuploidy)

Genomic Mutations Transmitted frequently T/F With reason

F only infrequently because most are incompatible with life

Aneuploidy - cell or organism with _______________________________ i.e. fewer or more chromosomes than usual

Causes of Aneuploidy 1.________ of _________ at the _____ meiotic division 2. _______ of the ________ in a chromosome at the ______ meiotic division 3. Non-separation of the _______ in a chromosome during _____ divisions 4. ______ lag

Non-disjunction; homologous chromosomes ; 1st Non-separation ; two chromatids; 2nd two chromatids ; somatic cell Anaphase

TYPES of inheritance ________ INHERITANCE ________ INHERITANCE

CLASSICAL NON CLASSICAL

Principles of classical Inheritance Mendel’s 1st Principle (The law of ______) Mendel’s 2nd Principle (The law of ____________)

segregation independent assortment

Mendel’s 1st Principle (The law of segregation) Genes segregate in the formation of ______

sex cells.

Mendel’s 2nd Principle (Law of Independent Assortment) The expression of a gene for any single trait is ______________

usually not influenced by the expression of another trait

Patterns Of Inheritance Classical __________ _____________ Non-classical  _____ Inheritance ________ Inheritance _____________ ____________

Dominant-Recessive Inheritance Sex-linked (XorY Linked) Inheritance Polygenic; Mitochondrial; Genomic imprinting; Gonadal mosaicism

Patterns Of Inheritance Non-classical  Polygenic Inheritance –dependent on the interaction of _______  Mitochondrial Inheritance –transmitted by ____________  Genomic imprinting  Gonadal mosaicism

numerous genes genes present on mitochondrial chromosome (a.k.a. maternal inheritance)

___________ (dwarfism)

Achondroplasia

Achondroplasia Dominant or recessive? Autosomal or Sex linked?

Dominant Autosomal

Neurofibromatosis Autosomal dominant or recessive?

Dominant

In autosomal dominance Patient may have unaffected parents T/F With reason

T Frequency depends on reproductive fitness ↓Penetrance and Variable Expressivity (V.E.) may alter Clinical features

Huntington's disease The gene for HD contains the instructions for making a large protein called _______.  An abnormal HD gene results in the production of __________  This abnormal protein builds up & causes _______, starting with those that are in the _______, a region of the brain that helps _________

huntingtin abnormal huntingtin protein, brain cells to die basal ganglia; coordinate movement

At present, there is a cure for HD T/F

F There isn’t

Neurofibromatosis 1 (NF1) Also known as _______disease Characterized by neurofibromas confined to the _______,______, and _______ It is also associated with _______ (café au lait spots),  freckles in the _____ and ____ region _______ and _______ of the Eye (Lisch nodules)

Von Recklinghausen’s skin, peripheral nerves and spinal nerve roots. hyperpigmented macules axilla and inguinal optic gliomas and iris hamartomas

iris hamartomas are also called _______

Lisch nodules

Marfan Syndrome  Rare inherited disorder of _____ resulting in  abnormalities of the eyes, lungs, heart, bones, and blood vessels Characteristic features include  Unusually __________  ____sightedness, tendency for the _____ of the eye to be ______.  Weaknesses in the ______ leading to severe problems of the _____ and ____

connective tissues long, slender arms, legs, and fingers; Near; lenses; dislocated blood vessels ; heart and aorta

Marfan syndrome Autosomal or sex linked? Dominant or recessive?

Autosomal dominant

Single largest category of Mendelian disorder is ????

Autosomal recessive

In autosomal recessive There is a/an ____eased incidence of parental consanguinity

incr

Albinism AR or AD?

Sickle Cell Anaemia AR or AD?

Late onset of disease Early onset of disease AD or AR?

AD AR

haemophilia Autosomal or X linked or Y linked Dominant or recessive

X linked recessive

DMD Autosomal or X linked or Y linked Dominant or recessive

X linked Recessive

______ muscular dystrophy is a milder form of Duchenne muscular dystrophy.

Becker

Hypophosphatemic (vitamin D resistant) Rickets Autosomal or X linked or Y linked Dominant or recessive

X linked Dominant

X-Linked Dominant Inheritance Affects either sex, but more _____ than _____

females males

X-Linked Dominant Inheritance There is male to male transmission T/F

F None

X-Linked Dominant Inheritance The child of an affected female, irrespective of its sex, has a ___% chance of being affected ___ the daughters , _____ of the sons, of an affected male are affected

50 all but none

hairy pinnae Autosomal or X linked or Y linked Dominant or recessive

Y linked Dominant

Y-linked Inheritance  Affects _____ gender

only males

Y-linked Inheritance All ____ of an affected male are affected

sons

TRISOMY ____ (Down’s syndrome)

TRISOMY ___ (Edward’s syndrome)

2nd most common autosomal aberration??

TRISOMY 18

2nd most common multiple malformation syndrome??

TRISOMY 18

Genetic Defects in Trisomy 18 1. ________-(90%) 2. ________-(10%) 3. ________ (very rare)

Meiotic nondisjunction Mosaicism Translocations

Sex chromosome disorders Are often easy to diagnose at birth T/F many are 1st recognised at ____

F difficult Puberty

Sex chromosome disorders The higher the number of sex chromosomes in both sexes the more the likelihood of _______

mental retardation

_______ disorders of sex chromosomes are far more common than those related to ___________

Karyotypic autosomal aberrations.

Which are better tolerated between Sex chromosome imbalances and autosomes imbalances

Sex chromosome imbalances are also better tolerated than those of autosomes.

Klinefelter - ____ Turner syndrome -____ Mixed Gonadal Dysgenesis (MGD)-______

47XXY 45 X 45X/46XY

Similarity between prader willi syndrome and angelman syndrome

Both exhibit mental retardation

Differences between prader willi syndrome and angelman syndrome Muscle tone Nickname Body ish? Behavior

Hypotonia; seizures Floppy babies; happy puppets Small hands, feet and short stature; ataxic gait Hyperphagia; inappropriate laughter

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Basic Genetics Flashcards

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