CS1204 Transfusion Medicine I - Genetic Principles

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Questions and Answers

What characterizes the cis position in ABO inheritance?

Both alleles are AB.

Both alleles are O.

One allele is AB and the other is O. (correct)

One allele is A and the other is B.

Which of the following correctly defines phenotype?

The combination of alleles inherited.

The observable characteristics of an individual. (correct)

The genetic makeup of an individual.

The position of genes on a chromosome.

Which term describes an individual with two identical alleles for a specific trait?

Heterozygous

Autosomal

Recessive

Homozygous (correct)

What does the term 'allele' refer to?

A variant form of a gene. Signup and view all the answers

What is true about blood group antigens?

Each individual receives a combination from both parents. Signup and view all the answers

What is a chromosome?

The unit of inheritance that carries genes. Signup and view all the answers

Which of the following statements about genes is true?

Genes encode instructions for building proteins. Signup and view all the answers

What does it mean if an organism is homozygous for a trait?

It carries two identical alleles for that trait. Signup and view all the answers

What does the locus refer to in genetics?

The specific location of a gene on a chromosome. Signup and view all the answers

Which term describes contrasting forms of a gene?

Allele Signup and view all the answers

How many chromosomes are present in a human somatic cell?

46 chromosomes Signup and view all the answers

Which of the following describes a phenotype?

The observable traits or characteristics of an organism. Signup and view all the answers

Which term refers to the different forms of a trait that can be passed from parents to offspring?

Allele Signup and view all the answers

What does the term 'phenotype' refer to in the context of ABO blood groups?

The observable expression of inherited traits Signup and view all the answers

Individuals with an AO genotype possess which ABO blood type?

Type A Signup and view all the answers

Which alleles are considered codominant in the ABO blood group system?

A and B Signup and view all the answers

What is the genotype for an individual with blood type O?

OO Signup and view all the answers

Where is the ABO gene located?

On chromosome 9 Signup and view all the answers

What does the term 'genotype' encompass?

The inherited alleles from parents Signup and view all the answers

What is a possible genotype for an individual with blood type AB?

AB Signup and view all the answers

If a child has blood type A, which of the following genotypes could the parents have?

AA and AO Signup and view all the answers

What is the basic unit of inheritance for traits such as blood group antigens?

Gene Signup and view all the answers

Which of the following best describes homozygosity?

Identical alleles are inherited at a chromosomal locus Signup and view all the answers

In genetic terms, what does the zygosity refer to?

The similarity or dissimilarity of genes at an allelic position Signup and view all the answers

How are most blood group genes inherited?

Through co-dominant traits Signup and view all the answers

Which statement accurately describes recessive traits?

Expressed only when identical alleles are present Signup and view all the answers

What is an example of a scenario displaying dosage in genetics?

Rh positive expression when homozygous Signup and view all the answers

Which alleles determine an individual's ABO blood type?

A, B, and O Signup and view all the answers

In genetic inheritance, what characteristic is attributed to co-dominance?

Both alleles are expressed equally Signup and view all the answers

What is the genotype for individuals with blood group B?

BB Signup and view all the answers

Which blood group does not have any antigens?

O Signup and view all the answers

What would be the possible blood group genotypes for someone with blood group A?

AA or AO Signup and view all the answers

What is the primary effect of the trans-position in the Rh blood group system?

Depressed D antigen production Signup and view all the answers

Cis and trans positions are specifically referenced for which blood group system?

Rh blood group system Signup and view all the answers

What is a distinguishing feature of individuals with blood group O?

They produce anti-A and anti-B antibodies Signup and view all the answers

What is the mode of inheritance for the O blood group?

Inherit two copies from both parents Signup and view all the answers

What happens to D antigen expression when C is in trans position to D?

It is suppressed Signup and view all the answers

Study Notes

Course Information

Course Title: CS1204 Transfusion Medicine I
Faculty: Faculty of Health Sciences
Diploma: Diploma in Medical Laboratory Technology
Date: 27/10/2023
Prepared by: Nor Raihan Mohammad Shabani

Topic 3: Genetic Principles in Transfusion Medicine

A gene is a segment of DNA that encodes a particular protein
Genes contain instructions for building one or more molecules that help the body work
Genes are the basic unit of inheritance, including blood group antigens
Genes are located in specific places (loci) along chromosomes
Chromosomes are the units of inheritance that carry genes
A human somatic cell has 46 chromosomes, 22 pairs of autosomes and 1 pair of sex chromosomes.
Genetics is the scientific study of genes and heredity
Genetic traits are passed from parents to offspring due to changes in DNA sequence
Genetic information is carried on double strands of DNA called chromosomes

Lesson Plan

Define these terms -Chromosomes -Gene -Locus -Allele -Silent gene -Phenotype -Genotype -Homozygous -Heterozygous -Cis and trans positions -Autosomal -Dominant and recessive

Summary Blood Group Antigens and Possible Genotypes

Blood group antigens are inherited characteristics
Every person inherits a combination of antigens from their parents

Different Alleles

Individuals with an AO genotype have an A phenotype.
People with an OO genotype have an O phenotype
The A and B alleles are codominant.
If someone inherits an A allele from one parent and a B allele from the other, their phenotype is AB.

Blood Groups, Antigens, and Antibodies

Blood Type A: A antigen, Anti-B antibodies, possible genotypes AA OR AO.
Blood Type B: B antigen, Anti-A antibodies, possible genotype BB OR BO.
Blood Type AB: A & B antigens, no antibodies, possible genotype AB.
Blood Type O: No antigens, Anti-A and Anti-B antibodies, possible genotype OO.

Zygosity

Zygosity describes the similarity or dissimilarity of genes at an allelic position on two homologous chromosomes.
Homozygous: Inheritance of identical genes at a chromosomal locus (e.g. KK or kk at the Kell locus)
Heterozygous: Inheritance of two different genes at a chromosomal locus (e.g. Kk at the Kell locus)

Dosage

A condition where a gene expression is stronger due to homozygosity (e.g. M+N-; Fya+Fyb-)
RBC antigen systems that display dosage
Rh
Lewis
MNS
Kidd (Jk)
Duffy (Fy)

Dominant and Codominant

Dominant: The characteristic determined by one chromosome takes precedence over the one on a different chromosome, (e.g. A/O types as A or D/d as D)
Codominant: Equal expression of two different inherited alleles in which neither is dominant over the other (e.g. A/B types as AB)
In codominance, both alleles are expressed, and their gene products are seen at the phenotypic level.

Recessive and Silent Gene

Recessive: the characteristic determined by the allele will be expressed only if the same allele is on the other chromosome. (e.g. O/O or D-negative d/d).
Silent gene: A gene that does not produce a detectable product (e.g., O, d, or h gene)

Genetic Inheritance of the ABO Blood Group

An individual's ABO blood type is determined by inheritance of one of three alleles (A, B, or O) from each parent
ABO blood types are inherited through genes on the long arm of chromosome 9; they don't change due to environmental factors.

9q34

Location, or locus, of the ABO gene, which codes for the ABO blood group

Phenotype versus Genotype

Phenotype: Result of reaction between red cells and antisera/observable expression of traits (e.g., group A or Rh positive)
Genotype: Actual genetic makeup/genetic information for a trait carried on each chromosome (e.g., O/O or A/O).

Position Effect

C trans-position effect: The D gene is in trans to the C gene (opposite sides). This can affect amounts of D antigen production. (e.g. Dce/dCe).
C cis-position effect: The C and D genes are on the same side/in cis, This can also affect amounts of D antigen production.(e.g. Dce/dce.)

Summary of Blood Groups

Blood type A: Possible genotypes AA and AO, A antigen, anti-B antibodies.
Blood type B: Possible genotypes BB and BO, B antigen, anti-A antibodies.
Blood type AB: Possible genotype AB, A and B antigens, no antibodies.
Blood type O: Possible genotype OO, no antigens, Anti-A and anti-B antibodies.

Cis and Trans Position

Two genes are inherited on different chromosomes, it's described as a trans position.
Two genes are inherited on the same chromosome, it's described as cis position. If C is trans to D, there may be a position effect on the expression (e.g., weakening/depression) of D antigen.

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Description

This quiz explores the genetic principles relevant to transfusion medicine, focusing on the role of genes and chromosomes. It covers topics such as inheritance, genetic traits, and the significance of DNA in blood group antigens. Test your understanding of genetic concepts fundamental to medical laboratory technology.