Genetics exam 1 Flashcards
what were the three big milestones?
-Gregor Mendel: the rules of inheritance
-James Watson and Francis Crick: the structure of DNA
-The Human Genome Project: the detailed analysis of human DNA
what are genes
the basic physical and functional unit of heredity. Made up of nucleic acids
what is gregor mendel rules of inheritance?
-Alleles of the same gene
separate during gamete
formation
– Alleles of different genes
are inherited
independently
whats an allele
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Nucleic acids
made of building
blocks called nucleotides
4 Nucleotides have three
components
– Sugar molecule (ribose or
deoxyribose)
– Phosphate molecule
– Nitrogen-containing molecule
(adenine, guanine, cytosine,
thymine, uracil)
4 RNA is ribonucleic acid
4 DNA is deoxyribonucleic acid
What is the signifigance of knowing the molecular structure of Dna?
Understanding the structure and function of DNA has helped revolutionise the investigation of disease pathways, assess an individual’s genetic susceptibility to specific diseases, diagnose genetic disorders, and formulate new drugs. It is also critical to the identification of pathogens.
What was the purpose and significance of the human genome project?
The project determined the sequence of nucleotides in the DNA of the human genome. Rough draft completed in 2002, completed officially in 2003.
genome
the collection of
DNA molecules that is
characteristic of an organism
Genomics
the analysis of
DNA sequences that make up
a genome
4 Genomics involves DNA
sequencing technology,
robotics, and computer science
DNA
DNA is the hereditary material of all life forms
except some types of viruses, in which RNA
is the hereditary material.
What’s the importance of sequencing the DNA of a genome?
provides the data to identify and catalogue all the genes of an organism
central dogma
The flow of information is DNA RNA protein.
- Some viruses can use RNA as a template for the
synthesis of DNA in reverse transcription.
-Many genes do not encode polypeptides; their end-
products are RNA molecules. This is becoming
increasingly important.
Genetic material(DNA) must have some characteristics
-Must be able to replicate
– Must contain information
– Must be able to change
DNA replication
-When the two parental strands are separated, the
separated strands can serve as template for the
synthesis of new strands.
-4 New strands are assembled by incorporating
nucleotides according to base-pairing rules.
-4 At the end of replication, each template strand is
paired with a newly synthesized partner strand.
-4 DNA replication is catalyzed by enzymes
Gene expression
-During transcription, an Rna molecule is synthsized from a DNA template
-This messenger RNA molecules contains the information needed to synthesize a polypeptide
-During translation, the triple codons in the RNA specify the incorporation of particular amino acids into a polypeptide chain
Proteome
the collection of all the
different proteins in an organism.
-Humans have between 20,000 and 25,000 genes in the genome and hundreds of thousands of proteins in the
proteome.
Proteomics
the study of all the proteins in the cell
what is the central dogma
-The flow of information is DNA goes to RNA which goes to protein.
- Some viruses can use RNA as a template for the
synthesis of DNA in reverse transcription.
- Many genes do not encode polypeptides; their end-
products are RNA molecules. This is becoming
increasingly important.
what is a genetic mutation
a change in one or more genes. Some mutations can lead to genetic disorders or illnesses.
classical genetics
-Based on analysis of the outcomes of crosses
between different strains of organisms.
-Can be coordinated with studies of the
structure and behavior of chromosomes.
-Encompasses transmission genetics and
studies of the nature of the genetic material
Population genetics
-Individuals within a population may
carry different alleles of genes.
-Population genetics is based on
analyzing allele frequencies in a
population and determining whether
these frequencies changes over time.
-Population genetics includes evolution
and the inheritance of complex traits.
Molecular genetics
-Studies the replication, expression, and
mutation of genes at the molecular level.
-Rooted in the study of DNA sequences
and the manipulation of DNA molecules.
Discoveries in genetics
-Discoveries in genetics are changing
procedures and practices in agriculture
and medicine.
-Advances in genetics are raising
ethical, legal, political, social, and
philosophical questions
What is the role of genetics in evolutionary biology? What is a phylogenetic tree?
If a trait is advantageous and helps the individual survive and reproduce, the genetic variation is more likely to be passed to the next generation (a process known as natural selection).
A phylogenetic tree is A way to compare organisms.
What are the three levels of genetic analysis
cytogenetic, biochemical, and molecular—are available to detect abnormalities in chromosome structure, protein function, and DNA sequence, respectively.
Prokaryote and eukaryote differences
Prokaryotic cells
- Does not have a membrane bound nucleus or organelles
- Most eukaryotic cells
contains a nucleus and organelles bound by plasma membranes
Prokaryote and eukaryote similarity
In both prokaryotic and eukaryotic
cells, the genetic material is organized into chromosomes.
gametes
sperm and egg cells
The cell cycle
The stages between one mitosis and the next, which include G1, S, and G2, are known collectively as the interphase.
-G1 phase
Cell increases in size
Cellular contents are duplicated
-S phase
DNA replication
Each of the 46 chromosomes (23 pairs) is replicated by the cell
-G2 phase
Cell grows more
Organelles and proteins develop in preparation for cell division
-M phase
Mitosis followed by cytokinesis (cell separation)
Formation of two identical daughter cells
mitosis stages
prophase, prometaphase, metaphase, anaphase and telophase and cytokinesis.
mitosis vs meiosis
mitosis makes identical cells meiosis makes eggs and sperm (gametes)
Meiosis stages
PMAT
Meiosis 1:
- Prophase I
-Chromosomes condense
· Synapsis- homologous chromosomes pair up
· Crossing over happens
· Metaphase I
· Tetrads line up at metaphase plate, (randomly) facing each pole
· Microtubules attach to kinetochore of 1 (of the 4) chromosome for both poles
· Anaphase I
· Pairs of homologous chromosomes separate
· Sister chromatids still attached at centromere and move as a unit toward the pole
· Telophase I and Cytokinesis
· Each half of the cell has a haploid set of chromosomes
· Each chromosome consists of 2 sister chromatids
· Meiotic division I is reduction division
· Cytokinesis occurs simultaneously and form 2 daughter cells
· MEIOSIS II
· NO CHROMOSOME REPLICATION
· Prophase II
· Spindle apparatus forms
· In late prophase, chromosomes start to move toward the middle of the cell
· Metaphase II
· Sister chromatids line up at metaphase plate
· Chromatids in each chromosome no longer genetically identical due to crossing over
· Kinetochores of sister chromatids attach to microtubules
· Anaphase II
· Sister chromatids separate
· Move towards opposite poles
· Telophase II and Cytokinesis
· Chromosomes are in opposite poles
· Nuclei begins to form
· Chromosomes begin to relax (decondense)
· Cytokinesis occurs simultaneously
· Results in 4 daughter cells
· Each daughter cells is genetically distinct from parents and other daughter cells
Crossing over when, how and what is occurring?
Occurs during Prophase I
· Homologous chromosomes pair up and swap genetic information
· Mom’s chromosomes pai up with the same chromosome from dad and swap genetic information
How is genetic variation generated in sexual life cycles/meiosis?
Mutations make alleles (different versions of a gene)
· Reshuffling of alleles during sexual reproduction
Independent Assortment of Chromosomes
Homologous pairs of chromosomes randomly line up on the metaphase plate
· Independent assortment- each pair of chromosomes sorts maternal and paternal homologues into daughter cells randomly
· # of possible combinations= 2n (n= haploid number)
· Ex. Humans n=23, therefore possible combinations=223
crossing over
Crossing overà recombinant chromosomes (combines genes inherited from both parents)
· Crossing over occurs at the beginning of Prophase I
· Homologous portions of sister chromatids pair up (very precise and specific)
· How does it contribute to genetic variation?
· Combines DNA from both parents to form a single brand new chromosome that did not exist previously
· Occurs 1-3 times per homologous pair per meiosis
Random fertilization
How does it add to genetic variation?
· Any sperm can fertilize any egg (ovum)
· Each zygote has unique genetic identity
· Not copies of parent cells
· Sexual reproductionà more genetic variations (due to mutations)
Mitosis phases
PMAT
- Before prophase interphase: chromosomes duplicate to produce sister chromatids
-Prophase: Duplicated chromosomes condense
-Metaphase: Duplicated chromosomes migrate to the equatorial plane of the cell and the nuclear membrane breaks down
-Anaphase: Sister chromatids of each duplicated chromosome move to opposite poles of the cell
-chromosomes decondense and new nuclear membrane forms
-Telophase : Membrane forms between daughter cells (cytokinesis)
spindle
a network of filaments that are formed during the cell division process.
plant vs animal cells
Animal cells each have a centrosome and lysosomes, whereas plant cells do not. Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not.
What is the purpose and end result of mitosis
The major purpose of mitosis is for growth and to replace worn out cells.
Meiosis is central to transmission genetics why?
it generates genetic diversity and maintains ploidy (the number of sets of chromosomes in a cell) through successive generations.
What makes a good model organism?
Typical characteristics of model organisms include developing to maturity rapidly, the ability to be easily manipulated, having a short life span, producing a large number of offspring and to having a sequenced genome, in addition to being well understood.
The principle of dominance (mendel)
In a heterozygote, one allele may conceal the
presence of another
the principle of segregation (mendel)
In a heterozygote, two different alleles segregate from each other during the
formation of gametes.
#3 comes after dihybrids….
The principle of independent assortment
The alleles of different
genes segregate, or as we sometimes say, assort, independently of each
other.
Application of mendels principles
Mendel’s principles can be used to predict the outcomes of crosses
between different strains of organisms.
Three methods to predict outcomes
– The Punnett Square Method
– The Forked-Line Method
– The Probability Method
Probability
the frequency of
that event in the sample space.
True breeding – what does this mean?
- parent plant that produce the same variety of offspring when self-fertilized
Law of segregation
Two alleles for a gene separate during gamete formation and rejoined at random during fertilization
