Bio 30 final review C2/C3 Flashcards
What is the difference between X-linked and autosomal traits?
sex-linked traits are dependent on the sex chromosomes whereas autosomal traits are not
What are the definitions of the following: Gene, Allele, Trait, Heterozygous, Homozygous, Dominant and Recessive
Gene: Molecular unit of heredity; it is what is passed down from one generation to the next
Allele: One or more alternate forms of genes
Trait:
Heterozygous: A genotype that contains two different alleles (ex; AA
Homozygous: A genotype that contains two of the same allele (ex: aa)
Dominant: A trait that is always expressed when the associated allele is present; represented by a capital letter
Recessive: A trait that is only expressed when the genotype is homozygous; represented by a lowercase allele
What is DNA replication
DNA replication is the process in which an original strand of nucleotides acts as a template strand for forming a new strand. this is known as semi-conservative replication
What are the steps of DNA replication
- The double helix relaxes and untwists using gyrase
- The hydrogen bonds between the nitrogen bases are broken using helicase, then the strands separate to become templates
- Free-floating nucleotides are lined up with the nitrogen bases in the template strands. Primase enzyme tells DNA polymerase where to build
- The free-floating nucleotides are glued into place using ligase
- the replicated strands are checked for errors using proofreading enzyme, any unresolved errors result in mutations
- two double stranded molecules of DNA now exist; each strand is half new and half og
What are the processes of protein synthesis
- Transcription (in the necleus)
- Translation (happens on ribosomes in the cytoplasm)
What are the steps of transcription
- DNA double helix untwists & separates using helicase to break the hydrogen bonds
- mRNA begins forming a complementary strand to one side of the DNA template using uracil(U) instead of Thymine(T)
- mRNA leaves the nucleus & goes into the cytoplasm
- mRNA carries instructions for protein synthesis for protein production to the ribosomes
What are the steps of translation
- Ribosomes attach to mRNA & expose one codon (3 bases) at a time
- mRNA codon directs the amino acid that should be placed within the protein sequence
- the amino acid attaches in place using its TRNA anticodon which is complementary to the mRNA strand
- a peptide bond forms between each amino acid, eventually the ribosome comes across a stop codon and detaches the protein.
What are the different types of mutations
Silent, missense, nonsense, frameshift, translocation, inversion.
What are the different categories of mutations
Point mutations: (Gene mutation) changes a single base pair of DNA sequence. May or may not change the sequence of amino acids.
Chromosomal mutations: alterations that affect the whole genes rather than individual nucleotides
What is a silent mutation
A mutation that dose not result in a change in the amino acid sequence
What is a missense mutation
A mutation that results in the single substation of one amino acids
What is a nonsense mutation
A mutation that converts a codon for an amino acid into a stop codon
What is a frameshift mutation
a mutation that causes the reading frame of the codon to change(adding/deleting bases)
What is a translocation mutation
The transfer of a fragment of the DNA from one gean in the genome to another location
what is an inversion mutation
The reversal of a segment of DNA with in a chromosome e
What is the difference between a genotype and a phenotype?
A genotype is the alleles with in the gene, a phenotype is the trait that is expressed by the gene
Who was Gregor Mandel? What did he do?
Gregor Mendel was an Austrian monk who is considered the “Father” of genetics for his contributions to field. He made his discoveries by experimenting on a common pea plant, from theses experiments he developed four principles called “Mendel’s laws of heredity”
What are Mendel’s Laws of Heredity
Some of the founding principles of genetics were based on Gregor Mendel’s experiments on pea plants. These laws are known as the law of unit characteristics, The law of dominance, The law of segregation, and The law of independent assortment
What is the law of unit characteristics?
The first law. “Traits are controlled by genes which occur in pairs (one copy from each parent)”
What is the law of Dominance
Second law. “The dominant form of a trait prevents prevents the expression of the recessive form”
What is the Law of Segregation
Third law. “During gamete formation (meiosis), homologous pairs separate and the gametes have one copy of each homologous chromosome”
What is the Law of Independent Assortment
Fourth law. “Chromosomes assort independently during meiosis; one chromosome dose not affect where any other chromosomes will move
What is a test cross and why is it performed
A test cross is the breeding of an individual with an unknown genotype for a given trait with another individual with a recessive genotype for the given trait. Test crosses are performed to determine the genotype of the unknown individual. If all children exhibit the dominant trait, the individual is homozygous dominant; if only some of the children exhibit the trait, the individual is heterozygous
What is incomplete dominance, give an example
Incomplete dominance is when two alleles are equally dominant but interact to produce a new phenotype. An example of this is red lilies and white lilies reproducing to create pink lilies.
What is co-dominance
Co-dominance is when two alleles are equally dominant, but both alleles are expressed equally at the same time. An example is when brown and white cows breed and produce half white and brown cows
Who was Thomas Hunt Morgan? What did he do?
-Thomas Hunt Morgan was an American geneticist who used fruit flies to study Mendel’s work on inheritance. When crossing male and female fruit flies, Morgan noted different ratios than would be expected from a typical monohybrid cross. Males and females seem to have different patterns of affectedness. He was the first scientist to discover Sex-linked inheritance patterns
What are the different inheritance patterns
Autosomal recessive, autosomal dominant, x-linked dominant, x-linked recessive
What is the phenotypic ratio for any dihybrid heterozygous cross
9:3:3:1
-9 Dominant-Dominant
-3 Dominant-Recessive
-3 Recessive-Dominant
-1 Recessive-Recessive
What does true breeding mean?
A parent is true breeding if it can only produce one type of gamete; its homozygous for all traits
What is a polygenic trait?
If a trait is regulated by multiple genes it is polygenic. An example of this is trait “a” controls hair colour in dogs whereas trait “b” controls the presence of hair
What are the general guidelines for the different inheritance pattern
-Auto-recessive: Trait skips a generation, could have unaffected parents (carriers), Often both parents of offspring who have the trait are heterozygous, only homozygous individuals have the trait, trait may appear in siblings without appearing in parents
-Auto-Dominant: Trait does not skip a generation, affected offspring can not have two unaffected parents
-X-linked recessive: More males are affected than females, All daughters of a male who has the trait are heterozygous carriers.
X-linked Dominant: All affected males have affected daughters, No male to male transition
What is gean linkage
Because there are many geans located on one chromosome, they are said to be linked and are most likely to be inherited together because they are not separated during meiosis. Linked genes are influenced by crossing over which can impact how they are inherited.
If crossing over occurs between homologous pairs, new combinations of alleles will result. The closer together two geans are on a chromosome the more, likely they will be inherited together. The further apart two genes are on a chromosome, the more likely that crossing over will separate them.
What is crossover frequency, what is the formula and its use?
Crossover frequency% (also called map units or centimorgans) = (number of recombinants/total number of offspring)x100
What does DNA stand for
Deoxyribose Nucleic Acid
Who are the people responsible for discovering DNA
Watson, Crick, Wilkins, and Rosalinda Franklin
What is DNA, What does it do?
DNA is a double-helix molecule located in the necoulous of a cell and contains the genetic information of an organism.
What is a nucleotide
An individual segment of a DNA chain
What are the parts of a nucleotide?
Deoxyribose sugar(DNA) or a ribose sugar(RNA), a phosphate group, and a nitrogen base
What are the categories of and respective base pairs for DNA
Purines: Adenine(A) and Guanine(G)
Pyrimidines: Thymine(T) and Cytosine(C)
pairs: A-T, G-C
What is the structure of DNA?
-2 strands of nucleotides
- each nucleotide has a phosphate, sugar(deoxyribose) & a nitrogen base (A, T, C, G)
-2 strands are twisted (dubble helix structure)
- strands run anti-parallel to each other
What is a protein and the importance of protein
protein is a structural component of all cells, it is made up of long, unique chains of amino acids and is linked by peptide bonds; proteins can range from 8-50,00 amino acids in length. Proteins are important because of their versatility in the body, things like hormones and enzymes are proteins, protein also builds muscle, repairs cell damage etc.
what are amino acids?
an organic molecule containing nitrogen and is the base unit for all proteins. there are 20 kinds of amino acids
What are the types of RNA
mRNA: (messenger RNA) coded from the DNA and uses the base uracil instead of thymine
tRNA: (transfer RNA) transports the amino acids from the cytoplasm of a cell the ribosome
Why is RNA used
RNA is smaller than DNA because its single-stranded, this means that RNA can leave the nucleus, unlike DNA. Because of its ability to leave the nucleus, RNA provides a way for genetic information to get to the ribosomes.
What are the differences between RNA and DNA
- RNA is smaller (single-stranded)
- Sugar in RNA is called ribose
- RNA has the nitrogen base Uracile U instead of thymine
Where does transcription take place
nucleus
where does translation take place
ribosomes in cytoplasm
What are the respective base pairs for RNA
A-U, C-G
What are the causes of genetic mutations
Spontaneous mutations: A mutation occurring as a result of errors made in DNA replication
Induced: A mutation caused by exposure, a mutagenic agent in the environment (chemical agent or radiation)
What are regulator genes and structural genes? what are their functions
Regulator(promoter) gene: tells structural genes to start or stop protein production
Structural genes: genes direct the assembly of amino acids into proteins
What is recombinant DNA technology
Technology that allows a segment of DNA that codes for a specific gene or protein to be transferred to the genetic material of a bacterium. This “recombined” genetic material will then begin synthesizing the protein instructed by the inserted DNA segment.
What is gel electrophoresis
DNA samples are prepared using restriction enzymes to cut up the DNA into fragments. Fragments are loaded into the wells of the gel on the electrophoresis machine and the machine is then ran. DNA segments are separated by size and can be compared to other samples
What phase does DNA replication take place
Interphase
