Week 4 DNA, Genetics, Patterns Of Inheritance Flashcards
DNA is composed of:
- Deoxyribose sugar
- A phosphate
- A base
A DNA base includes:
- Thymine
- Cytosine
- Adenine
- Guanine
A single strand of DNA is formed between the sugars and phosphates of nucleotides and is know as:
Sugar-phosphate backbone
Define complementary base pairing:
- Exclusive interaction between A and T involving 2 hydrogen bonds
- Exclusive interaction between G and C involving 3 hydrogen bonds
Pyrimidine bases are:
T and C with 1 nitrogen ring
Purine bases are:
A and G with 2 nitrogen rings
DNA plus protein
Chromatin
A process that involves evaluation of the number and content of the chromosomes.
Karyotyping
Involves division of the nucleus.
Mitosis
Involves division of the cell
Cytokinesis
DNA replication requires this to make a copy of the genetic info in each chromosome.
DNA polymerase
Since each resulting DNA molecule contains one original strand and one newly synthesized strand, DNA replication is termed
Semiconservative
Original DNA strand is marked with this so that DNA repair enzymes can identify mistakes.
Methyl group
Mutations in germline cells can be
Inherited
Mutations in somatic cells are
Not inherited
The genetic material is translated into protein by first being converted into an RNA molecule in the nucleus through a process called
Transcription
The RNA molecule exits the nucleus to the cytoplasm, where it is converted into protein info through a process called
Translation or protein synthesis
RNA is a macromolecule similar to DNA except:
- RNA is single stranded
- The sugar is RNA is ribose
- Uracil replaces thymine
This is 3 nucleotides in the messenger RNA (mRNA) sequence that specify an amino acid
A codon
Mutations that do not change the amino acid are called
Silent mutation
Mutations that alter the amino acid and may or may not alter protein structure and this function are called
Missense mutations
Other mutations may introduce a stop to protein synthesis and are called
Nonsense mutations
Somatic cells have 2 copies of each chromosomes and are called
Diploid
Gametes have only one copy of each chromosome and are called
Haploid
Involves the division of the nuclear material of a cell.
Mitosis
Stages of mitosis
Prophase, metaphase, anaphase, telophase
Phase of mitosis were nuclear membrane dissolves and 2 copies of each chromosome (sister chromatic) attach at the centromere
Prophase
Phase of mitosis where chromosomes are highly condensed and line up on the equatorial plane of the cell
Metaphase
Phase of mitosis where sister chromatids and chromosomes are pulled apart
Anaphase
Phase of mitosis where nuclear membrane forms around the 2 sets of chromosomes
Telophase
Mitosis is followed by the forming of 2 daughter or progeny cells called
Cytokinesis
Involves reduction divisions that take a diploids cell and creates a haploid cell with half the chromosomal info
Meiosis
Reduction division stage that results in the formation of 2 haploid cells per diploid cell, and in which homologous chromosomes separate but sister chromatids (copies) remain together
Meiosis I
Equatorial division where sister chromatids are separated
Meiosis II
Ensures that genetic info in the offspring is unique
Genetic recombination
Segments of DNA that control biological characteristics that are passed down from generation to generation (hereditary traits)
Genes
Genetic makeup of an organism
Genotype
The observable characteristics of an organism produced by the interaction between genotype and the environment
Phenotype
A genetic change found in the gametes and thus one that can be transmitted to offspring or inherited
Germline mutation
A genetic change in one of the cells of the body that can not be transferred to offspring or inherited
Somatic mutations
If both gene copies are the same at a specific allele
Homozygous trait
If there are 2 different alleles of a particular gene at a locus
Heterozygous
This principle states that 2 members of a gene pair (alleles) separate from each other in the formation of the gametes and that half of the gametes carries one allele and the other half carries the other allele.
Principle of segregation
Principle that states genes for different traits assort independently of one another in gamete production and genes controlling different individual loci are not transmitted together to the portent but rather are inherited independently of one another
Principle of independent assortment
Caused by a single defective or mutant gene that may be present on one or both alleles
Single-gene disorder
Caused by an excess or deficiency of genes contained within a whole chromosome or chromosomal segment
Chromosomal disorders
Caused by a combo of variations in a number of genes that together produce or predispose an individual to a serious defect that are often in concert with environmental factors
Multifactorial inheritance disorder
A few disorders are characterized by different phenotypes depending upon whether the mutation was obtained from the mother or the father
Genomic imprinting
Examples of single-locus genetic disorders that have autosomal recessive traits
CF and SCD
Examples of single-locus genetic disorders that have autosomal dominant traits
Achondroplasia (dwarfism) and Marfan syndrome (connective tissue defects)
Examples of single-locus genetic disorders that are x-linked recessive
Duchenne muscular dystrophy, hemophilia A, and G7PD deficiency
These affects energy metabolism, present with multiple copies, and are inherited from the mother only
Mitochondrial disorders
An autosomal dominant disorder or the connective tissue with not structural changes found in the heart, blood vessels, joints, and eyes. People tend to unusually tall, with long limbs and digits
Marfan syndrome
What gene is mutated in Marfan syndrome?
FBN1 gene which encodes the connective tissue protein fibrillin-1, a component of the extracellular matrix including formation and maintenance of elastic fibers. It’s on chromosome 15
Results from a deficiency of clotting factor VIII that is caused by an inherited x-linked recessive trait with the defective gene located on the X chromosome.
Hemophilia A
Hemophilia affects only
Makes while women are carriers
Treatment for hemophilia
Includes replacing factor VIII. Mild hemophilia may be treated with desmopressin which helps the body release favor VIII stored within lining of blood vessels
Mutations in this often result in disorders that reflect reduced energy production such as poor growth, loss of muscle coordination, and muscle weakness.
Mitochondrial DNA
Complete sets of extra chromosomes
Polyploidy
Chromosome number that is not 23. An example is trisomy 21. A common cause is nondisjunction.
Aneuploid
Occurs due to nondisjunction and is associated with advanced maternal age.
Trisomy 21
This occurs during meiosis when there is failure to separate chromosomes (meiosis I) or sister- chromatids (meiosis II)
Nondisjunction
Absence of all or part of the X chromosome. Individuals exhibit short stature and lack ovaries and as a consequence there is a lack of secondary sexual characteristics.
Turner syndrome
One or more additional X chromosomes with a normal male composition (XY). Individuals exhibit testicular dysgenesis, enlarged breasts, small testes, and inability to produce sperm.
Klinefelter syndrome
Translocations 9 and 22 for a truncated chromosome 22 called
Philadelphia chromosome associated with leukemia
