U4 T1 - DNA, Genes, Flashcards
What is deoxyribonucleic acid (DNA)?
It is a double-stranded molecule that occurs bound to proteins (histones) in chromosomes in the nucleus
What are the four bases in DNA?
Adenine, Thymine, Guanine and Cytosine
What is the structure of DNA?
It is a double helix formed with two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs.
What role does helicase play in DNA?
They separate double-stranded DNA into single strands allowing each strand to be copied.
What happens in Meiosis I?
Homologue pairs separate during a first round of cell division,
What happens in Meiosis II?
Sister chromatids separate during a second round
How does the process of crossing over and recombination contribute to genetic variation?
Homologous chromosomes – 1 inherited from each parent – pair along their lengths, gene by gene.
Define the term genome
The haploid set of chromosomes in a gamete
Define the term Gene
Genes are made up of sequences of DNA which are the basic unit of heredity information passed from parent to child.
What do gene’s include?
coding and noncoding DNA, functional RNA, centromeres, telomeres and introns
explain the process of protein synthesis
transcription of a gene into messenger RNA in the nucleus translation of mRNA into an amino acid sequence at the ribosome
What is the purpose of gene expression?
It is to synthesise a functional gene product (protein or functional RNA)
What are the factors that regulate the phenotypic expression of genes during transcription?
Transcription factors which bind to specific DNA sequences and regulate gene expression.
What does differential gene expression do to cell differentiation?
It regulates cell differentiation for tissue formation and morphology
Example of a transcription factor that regulates morphology
HOX transcription factor family
How can mutations in genes and chromosomes can result from errors in DNA replication?
It can cause cell division and damage mutagens
Explain how non-disjunction leads to aneuploidy
It is from the failure of the sister chromatids to separate during anaphase II
describe how inherited mutations can alter the variations in the genotype of offspring.
The mutations cause changes in the proteins produced, and therefore it’s structure or function
Define polygenic inheritance
Polygenic inheritance refers to the inheritance of a trait governed by more than one genes.
Describe the process of making recombinant DNA
isolation of DNA, cutting of DNA (restriction enzymes) insertion of DNA fragment (plasmid vector) joining of DNA (DNA ligase) amplification of recombinant DNA (bacterial transformation)
What are the applications of DNA sequencing
to find genes, segments of DNA that code for a specific protein or phenotype
Explain the purpose of polymerase chain reaction (PCR) and gel electrophoresis
the goal of PCR is to make enough of the target DNA region that it can be analyzed or used in some other way.
Explain Interphase
The cells are growing and chromosomes are duplicated in preparation for cell division
Explain Prophase
The chromosomes condense making them easier to pull apart. The nuclear membrane dissolves freeing the chromosomes
Explain Metaphase
Short resting phase wherethechromosomes line up on theequator of the cell. Centrosomes are now at oppositeends with spindle fibers attachedto the centromeres
Explain Anaphase
The centromeres divide - spindle fibers contractand chromosomespull toopposite poles
Explain Telophase
The nuclear envelope that hadbroken down reforms around eachof the new sister chromatids
Explain Prophase II
In each of the daughter cells, a new spindle apparatus forms, the nuclear envelope breaks down, and the chromatin condenses into chromosomes again.
Explain Metaphase II
The chromosomes line up along the metaphase plate.
Explain Anaphase II
Separation of the sister chromatids occur in this phase
Explain Telophase II
The chromosomes gather at the 2 poles of the cell and the cell divides via cytokinesis forming 2 daughter cell
