Genetics Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What is the structure of the DNA?
Found in large, round circular chromosome in bacteria
Are there multiple linear DNA chromosomes in the nucleus of plant and animal cells?
True or False
True
Where else could DNA be found?
Inside a protein coat of a virus
How many chromosomes are there in the human cells?
46 chromosomes
What are monomers?
Monomer of DNA is a nucleotide
How many parts is the nucleotide made of?
3 parts
Name the 3 parts of the nucleotide
Five carbon sugar
Phosphate group
Nitrogenous base
How many parts is the nucleoside made of?
2 parts
Name the 2 parts of the nucleoside
Sugar(pentose)
A nitrogen base only
4 bases of nitrogen bases in DNA
Guanine
Adenosine
Cytosine
Thymine
What is the base pairing in DNA Double Helix?
A pairs with T (vice versa)
C pairs with G (vice versa)
DNA is folded and coiled around protein called…
histones—> careful packing nucleus
What are alleles?
Different variations of the same gene
Example of an allele
Trait of hair colour has various alleles such as brown, blonde, black and red hair
What is the result of TTGACA?
AACTGT
Process of human offspring
Zygote–> Embryo–> Fetus–> Infant
Who is known as “the father of genetics”
Gregor Mendel
Plants reproduce sexually so they undergo meiosis
True or False?
True
What are the 2 rules of the Principal of Complete Dominance?
- Occurs when there are only two alleles of a single gene
- Dominant allele will mask recessive allele
How is theDominant Allele represented?
Capital Letters (T, C, A)
How is the Recessive Allele represented?
Lower Case Letters (t, c, a)
Homozygous Dominant
TT
Homozygous Recessive
tt
Heterozygous Dominant & Recessive
Tt
Genotype
‘genes’ found in the two chromosomes of an organism
- ie. TT, Tt, or tt
Phenotype
physical appearance of the organism
- ie. tall or short
True Breeding
organism that always breeds the same results without any variance
Purebred
self fertilizes to produce offspring identical to the parent
P1
Parental Generation
F1
First Filial Generation
What are Punnet Squares?
- determine probability of having an offspring with a particular genotype and phenotype
- calculate the chance of a particular outcome
Dihybrid Cross
inheritance of two traits
What is the Law of Segregation?
allele inherited from each parent has a 50% chance of being passed to offspring in egg/sperm/pollen cell
What is the Law of Independent Assortment?
each trait (gene) is inherited independently of others
Incomplete Dominance
neither allele is dominant instead they blend together to create a new blended phenotype
Codominance
both alleles are dominant so they can both show up togther
co–> together
Example of Codominance in Real Life?
Human Blood Types
- occurs in ABO blood groups
How is each blood type caused?
Presence of proteins called antigens on the surface of the blood cells
Name the 3 different antigens
A antigens
B antigens
no(zero) antigens
Are both type A and type B blood dominant over type O blood?
True or False
True
If an individual carries both type A blood and type B blood , how are the allels expressed together?
Type AB blood
How are the two dominant alleles and one recessive allele represented as?
Two dominant alleles: I^A and I^B
Recessive allele: i
Genotype of type O blood
ii
Genotype of type AB blood
I^A I^B
Genotype of type A blood
I^A I^A or I^Ai
Genotype of type B blood
I^B I^B or I^Bi
Type O blood is a universal recipient
True or False
Flase, it is a a universal donar which can donate blood to any blood groups
Type AB blood is a universal recipient
True or False
True, it can recieve blood from any blood groups
Does type O blood have A and B antigens on the surface of its cell?
No, type O blood has neither A or B antigens on the surface of its cell?
Reaction of type O blood when donated to any patient
No reaction with either anti A or anti B antibodies
Reaction of type A, B or AB blood is donated to a patient with type O blood
Patient’s immune system will see the A, B, or AB antigens as foreign and ‘attack’ anti bodies –> causing clumping(agglutination)
What is the 3rd type of surface antigen on red blood cells?
Rh factor
What is Rh factor?
It determines what type of blood can be given to a patient
If a patient is Rh positive, what does it mean?
- they don’t have anti-Rh antibodies
- they can accept either positive or negative blood
If a patient is Rh negative,
- they should stick to negative blood
How can the Rh factor affect pregnancy?
If mom has Rh negative, the immune system may attack the uterus if baby has Rh positive
Sex Linked
Genes on the X and Y chromosomes which are called X linked or Y linked
Autosomes
22 pairs of non-sex chromosomes that contain genes for anything that does not relate to sex determination
Karyotype
Image of a person’s chromosomes under a microscope
It is the mother’s egg determines the sex of the offspring?
True or False
False, it is the father’s sperm that determines the sex of the offspring
Male–> XY
X-linked traits
-carried on the x chromosome
If x-linked trait is recessive
- females carry a second X chromosome
- do not express the trait
- mothers–> carriers of the disorders
What is Hemophilia?
A disease caused by a recessive X linked gene. It has an inability to properly clot blood
Example of Hemophila
small cut or bruise–> uncontrolled bleeding–> can be fatal
Hemophilia is also referred as…
“The Royal Disease”
Hemophilia indicated as…
X^h
X^H
Normal–> dominant allele
X^h
Hemophilia–> recessive allele
Pedigree
Chart showing the lineage of family members
Huntington’s disease
A progressive brain disorder caused by a defective gene. Results in the death of brain cells
Huntington’s disease also known as….
Huntington’s Chorea
What drugs are given to control the movement of the Huntington’s disease?
Anti psychotics
What is the probability of inheriting the gene of the Huntington’s disease?
50% chance of inheriting the gene from affected parent and since its dominant, one mutant copy is enough to give you the disease
When do the symptoms of the Huntington’s disease arise?
After the age of 35 to 44
Can the Huntington’s disease symptoms arise in childhood?
Yes, symptoms may also arise in childhood itself if repeat count is very high
What are the two major types of genetic disorders?
Mutations and Nondisjunction errors
Mutations
Errors in DNA itself
Nondisjuction errors
when meiotic process is completed abnormally
Gene
Portion of the DNA molecule found on a chromosome
What is the function of a gene?
Codes for a single polypeptide
Polypeptide
Chain of amino acids
Point Mutations
An error at a single point in the DNA
State the 3 reasons why point mutation may occur
- deletion of a base pair
- shifting of a base pair, cause by inserting or deleting a nucleotide(frame shift)
- substitution of a base pair
Example of Point Mutation
Sickle Cell Anemia
Sickle Cell Anemia
Error in DNA which results in all blood cells(red) taking on an irregular curved shape(sickle shape)
Name the 5 other types of mutations that also occur on chromosomes
Duplication Inversion Deletion Insertion Translocation
Duplication
A part of chromosome is duplicated more than one time
Inversion
A part of chromosome is inverted on the same chromosome so the genes on that segment are in a different location
Deletion
A part of chromosome is missing
Insertion
A part of chromosome is inserted onto another chromosome
Translocation
A part of chromosome is translocated to the end of another chromosome
Nondisjunction
An error that occurs in meiosis. Individual chromosomes moving to different cells
Chromosomal Disorder
Person’s cells do not have the correct number of chromosomes
Name the 4 major disorders caused by nondisjunction
Down’s Syndrome
Klinefelter Syndrome
Turner Syndrome
Edward Syndrome
How is Down Syndrome caused ?
By the prescence of an extra chromosome 21
6 Clinical Characteristics of Down Syndrome
- poor muscle tone
- short and broad hands with single crease across palm on one or both hands
- slanting eyes with folds of skin at inner corners
- broad feet with short toes
- flat bridge of the nose
- small head and mouth
How is Klinefelter Syndrome caused?
A male has two X chromosome and one Y chromosome
When do the symptoms become apparent for Klinefelter Syndrome?
In puberty, when secondary sexual characteristics fail to develope(develop late)
How does the Klinefelter Syndrome affect a male?
Testicular changes occur that eventually result in infertility for majority of those affected
Treatment of Klinefelter Syndrome
They should be treated with testosterone, usually at the age of 11 or 12 years of age or after the mentioned age
How is Turner Syndrome caused?
A female lacks one or a part of one of the X chromosomes
9 Symptoms of Turner Syndrome
- short stature - lack of breasts - no periods
- a webbed neck - infertility - diabetes
- undeveloped ovaries
- increased rist of heart disease - osteoporosis
Treatment of Turner Syndrome
Treated with growth hormones and estrogen therapy
How is Edward Syndrome caused?
Person’s cells have three copies of chromosome 18
Symptoms of Edward Syndrome
Severe intellectual disabilities and their skeletons are malformed
Disadvantage of Edward Syndrome
Most people with this syndrome die in infancy
Genome
Total genetic information
Reproductive Technology
The use of technology to assit or enhance reproduction in humans or other organisms
Process of Superovulation
- mom injects hormones to cause maturation and release of more than one egg
- multiple injections over days required to trigger many follicles to mature
Process of Artificial Insemination
Partner’s or donor’s sperm injected into vagina
Process of Intrauterine Sperm Injection
- partner’s or donor’s sperm injected directly into uterus
- bypass difficult journey through cervical mucus
Process of In Vitro Fertilization (IVF)
- mother’s ovaries stimulated to super ovulate (hormone injections)
- eggs are retrieved from both ovaries using a long thin needle and ultrasound to provide technician with visualization
- sperm extracted and combined with eggs in petri dish in laboratory
- multiple zygotes (fertilized eggs) are created
- zygotes are watched closely for signs of healthy cell division
- only two or three healthy dividing embryos are inserted into Mom’s unterus (one injected with hormones to prepare her body for pregnancy)
- possible fraternal (dizygotic) twins or triplets could result if more than one embryo implants
Process of Intracytoplasmic Sperm Injection (ICSI)
- sperm is injected directly into egg
- useful for sperm that have difficulty dissolving the later surrounding the egg, the “zona pellucida” and penetrating the egg’s cell membrane
Process of Pre -implantation Diagnostic Testing (PGD)
- 5 or 6 days afte in vitro fertilization, a biopsy of the dividing embryo is performed, where a small sample of cells is removed
- these cells are tested for the ‘condition of interest’ and the embryos predicted to be unaffected are transferred to the woman’s uterus
Goal of Cytoplasmic Transfer
Providing new mitchondria to egg
What age group is the Cytoplasmic Transfer helpful to?
Helpful for mother who are older (45+) and embryos are less viable due to insufficient mitochondria in egg
