Lecture 11- Genetics Flashcards
What is studying genetics?
Considered to be the study of heredity such as study of how traits are passed from generation to generation
What is the dominant Allele?
An allele that is expressed in the phenotype when when only one copy is present
What is recessive allele?
An allele that is only expressed when two copies are present in the genotype.
What did Mendel discover to help him be identified as the first geneticist?
Part of findings found that peas get one version of each trait from each parent (allele)and that some seemed to be dominant whilst others were recessive.
What did Mendel discover about expression of dominant traits?
Dominant traits are expressed in an organism’s phenotype
What did Mendel discover about expression of recessive traits?
Recessive traits are only expressed in absence of dominant trait.
What does Mendelian inheritance suggest?
Phenotype traits will depend on your parents, as you receive an allele of each gene from each.
eg dimples are dominant but even if both parents have dominant and recessive, the proportion will be 3:1.
What are the 2 fundamental laws of the Mendelian inheritance?
Segregation
Independence
What is Segregation regarding mendelian inheritance?
Traits are either dominant or recessive
What is Independence regarding Mendelian inheritance?
Varieties of each trait sort independently of each other
What was discovered in current research due to being able to look closer than Mendel?
Deoxyribonucleic acid (DNA) can be found in the nucleus of every cell of an organism. It is composed of two chains of nucleotides that coil around each other to form a double helix.
What are the 4 nucleotides?
A= Adenine T= Thymine G= Guanine C= Cytosine
What goes with Adenine (A) in the chains?
Goes with Thymine (T)
What goes with Guanine (G) in the chains?
Cytosine (C)
What does the DNA double helix contain?
This double helix contains the genetic instructions for the development, functioning, growth and reproduction of all known biological organisms.
This means that the entire DNA of a being can be found in each individual cell.
What is the process of translation in DNA?
The strands are “unzipped” and read by ribonucleic acid (RNA) molecules to produce protein strands.
What occurs in the process of DNA to chromosomes?
-When in a cell’s nucleus, these long strands of DNA are called chromatids and are usually tangled together when a cell is active.
-When a cell needs to divide (mitosis), chromatids undergo condensation (the act of coiling tight like a spring to form a chromosome).
What happens during chromosomes to genome?
- Typical humans have 46 chromosomes (23 pairs). All pairs are XX, aside from the final pair which may vary. This pair codes for biological sex, with biological females having XX and males having XX - Individual sequences of DNA on these chromosomes are called genes, with humans possessing between 20,000 to 25,000 genes. The aggregate of these genes is called a genome.
What happens within genes?
-Some phenotype traits may be programmed by a single gene (pleiotropic), while others may be influenced by a combination of genes (polygenic).
Eg gene that codes for ear wax is on chromosome 16 (locus). This gene has two versions (alleles); a dominant version for wet ear wax and a recessive version for dry ear wax.
What are the 3 suggestions that challenge the idea of Mendel’s laws?
X-linked conditions
Sporadic mutations
Polygenic traits
What are X-linked conditions?
Some recessive traits are more prevalently expressed in males when compared to females. This is because they may not have a dominant allele on their (much shorter) Y chromosome
What are some examples of x-linked conditions?
Colorblindness= First reported case of human X linkage
Turner syndrome= Affects females, X partially missing, 1/2,500
Triple X syndrome= Individuals with three X chromosomes, typically assigned female at birth. Most have no severe physical differences but may have a slightly taller height and an increased risk of mild developmental and learning challenges.
What are Sporadic mutations?
Caused by errors or interference in typical cell division. These mutations can happen naturally or be the result of environmental factors
What are 2 examples of Sporadic mutations?
-Down syndrome, affects 1/1000, due to trisomy (extra version) of chromosome 21, symptoms incl facial dysmorphology -Williams syndrome, affects 1/18,000, due to micro deletion on chromosome 7, symptoms include facial dysmorphology
What are Polygenic traits?
These conditions or disorders reply on coding from multiple genes and may not consistently follow Mendelian rules.
Eg SZ, affects 20M worldwide, individuals are considered to be genetically predisposed to develop schizophrenia, suggesting a clear genetic basis.
What are genomic studies?
Inspects the genome of specific groups, identifies allele commonalities eg studying an extended family prone to Huntington’s helped identify the genetic markers
What are targeted mutations?
Mutated lab produced genes are inserted into chromosomes w/ 2 types: -Defective and failing to produce specific functional protein
-Produce new or different proteins
What is genetic engineering?
-Technology such as CRISPR allow us to directly edit our own genome
-Currently being used to tackle diseases such as HIV, cancer
What is the definition of genotype?
The genetic makeup of a biological organism
What is the definition of phenotype?
Observable characteristics of a biological organism. Can be physical or behavioural
What is the definition of heredity?
Passing of physical and mental characteristics from one generation to another
What is the definition of DNA?
Self replicating material found in nearly all living organisms, carrier of genetic information used to instruct formation of proteins
What is the definition of RNA?
A messenger that carries instructions from DNA
What is the definition of translation?
The act of turning genetic information found in DNA into proteins
What is the definition of a chromatid?
Long strands of DNA found in the nucleus of active cells
What is a chromosome?
Long DNA molecule with part or all of the genetic info of an organism.
What is the definition of a gene?
Single strand of functional DNA on a chromosome.
What is the definition of a genome?
A collection of genes
What is a locus?
Term to describe a single strand of functional DNA on a chromosome
What is an Allele?
Term used to describe different version of a gene and can be dominant or recessive
What is the definition of Pleiotropic?
Traits that are coded by a single gene within a genome
What is the definition of Polygenic?
Complex traits that are coded by multiple genes within a genome
