Reproduction & Inheritance Flashcards
Where is circular DNA found
Nucleoid of prokaryotes & mitochondria in eukaryotes
The mendelian definition of a gene
Unit of inheritance for a specific trait
Mandelian definition of an allele
A variant of a gene that codes for a specific form of the trait
Mendelian definition of genotype
Collection of alleles in question for an individual
Mendelian definition of phenotype
Observable traits of an individual
Mendelian definition of dominant allele
The allele expressed as a phenotype if present
Mendelian definition of recessive allele
The allele expressed are a phenotype if only it is present
What is the p generation? (Mandelian genetics)
Parental generation
What is the f1 generation? (Mandelian genetics)
First filial generation, offspring
What is the f2 generation? (Mandelian genetics)
Second filial generation, off spring of f1
What is a homozygote?
Individual with 2 identical alleles
What is a Hetrozygote ?
Individual with 2 different alleles
What is a monohybrid punnet square?
Punnet square where only one trait is considered
What is a dihybrid punnet square?
Punnet squat with 2 traits
Mendel’s first law
Law of dominance: some alleles are dominant & others are recessive, if 2 homozygotes with different alleles breed then the offspring will all be heterozygotes with the phenotype of the dominant allele
Mendel’s second law
Law of segregation: during gamete formation the alleles of each gene separate into separate gametes
Mendel’s third law
Law of independent assortment: alleles are past on separately of each other,
What is codominance? (Mendelian genetics)
Both alleles of a heterozygote are fully expressed thus traits are neither dominant nor passive
What is incomplete dominance? (Mendelian genetics)
When the heterozygous phenotype is distinct from the 2 possible homozygous phenotypes, ex colors of flowers mix into a new color
What do circle, squares, lines, blank & shaded in a pedigree diagram?
Circle: female
Square: male
Line: breeding
Blank: condition is not expressed
Shaded: condition is expressed
How many out of 46 are sex chromosomes?
2
Male chromosomes
Xy
Female chromosomes
Xx
What is autosomal dominant? (Pedigrees)
Allele is dominant & not x-linked
What are the 44 non sex chromosomes called?
Autosomal chromosomes
What is autosomal recessive? (Pedigrees)
Allele is recessive & not x- linked
What is x- linked dominant? (Pedigrees)
Allele is dominant & x-linked
What is x- linked recessive? (Pedigrees)
Allele is recessive & x-linked
What are histones?
Proteins that wrap DNA
What are nucleosome?
DNA wrapped twice around a core of 8 histones
What is a 30-300 nm fibre
A fibre formed from nucleosomes
What does chromosomal theory of inheritance state?
Chromosomes are the vehicles of genetic heredity
What are alleles carried on?
Chromosomes
How are genes linked?
By being carried on the same chromesome
What does it mean that genes are unlinked?
Genes are found on different chromosomes
When is independant important?
When genes are not linked
What is genetic recombination?
Random crossing over that occurs during meiosis & the Mendelian genetics dash hold
What makes separating genes during crossing over less likely?
The closer the genes are together
What arecell junctions?
Points of contact between cells
What are the 4 types of cell contact? & where are they found?
Tight junction: water tight seal connecting 2 cells where nothing can pass through, intestines, bladder & other places where you don’t want leaking
Desmosomes: connect Via cytoskeleton & hold 2 cells together, strongest type, things can flow between, stress resisting, skin, intestines, cardiac muscles
Gap junction: tunnel between cells allowing fluid to flow between & through, found in cells that spread action potentials, cordial cells, neurons
Plasmodesmata: only in plant cells, allows cytosol to flow between cells
What is the extracellular matrix / ECM & what is it responsible for?
Area outside cell responsible for coordination of cells & formation of tissue
What does the ECM play a role in?
Holding cells together (to form tissue), cell communication & cell migration
What are the 3 stages in cell signaling?
1 reception of signalling molecule
2 transduction, signal received will se converted into a new signal
3 cellular response
What are the two types of receptors in cells?
Internal & external
What is a different name for the signalling molecule?
Ligand
For an internal receptor to receive the ligand what does it have to be? & what type ligands are they?
Small or hydrophobic so it can enter the cell . Steroid hormones, thyroid hormone or nitricoxide
What ar the 2 types of internal receptors?
Nuclear receptor & cytosolic receptor
Different name for external receptors
Membrane receptors
What kind of ligands reacts with membrane receptors?
Hydrophilic receptors / ligands which can’t cross the membrane like epinephrine
What is the membrane receptor called?
Gpcr, g- protein couple receptor
Definition of gpcr
Transmembrane protein receptor that span the membrane 7 times
How many types of nucleotides are there?
4
What are the 2 invariable components of nucleotide?
Five carbon sugar & phosphate (sugar phosphate backbone)
What is the variable part of nucleotides? & how many different ones are there?
Nitrogenous base,4
The different types of nitrogenous bases
Adenine ( purine, 2 rings), guanine (purine), thymine ( pyramidine, 1 ring ) & cytosine (pyramidine)
What is the b-n-glycosidic bond in a nucleotide?
The bond between the sugar & the nitrogenous group
What is the phospho-ester bond in a nucleotide?
Bond between the the phosphate & the sugar
What is the phosphodiester bond?
Bond between the sugar, phosphate & new sugar modecuce, bridge
Which Carbons have the phosphoDiester bonds?
The 3’ & 5’
What kind of bonding is DNA
Antiparallel
How many & what kind of bonds are between the different kind of nucleotides?
Guanine & cytosine: 3 hydrogen bonds
Adenine & thymine: 2 hydrogen bonds
What is a nucleoside
Sugar & nitrogenous base (without the phosphate)
How many different ways of genetic replication are there? & what are they called
3: semiconservative model, Conservative model, dispersive model
What kind of model is DNA replicated after?
The semiconservative model
What enzyme is used during initiation of replication in DNA? & what does it do?
Helicase, breaks off hydrogen bonds between nucleotides & creates replication bubble
What unwinds the helix during DNA replication?
Topoisonerase
What does RNA have instead of thymine?
Uracil
Why do Okazaki fragments occur?
Because DNA can only be formed going 5’ → 3’ as there can only be added to the 3’ end
What fixes the nicks & okazaki fragments?
DNA ligaze
What is it called when DNA goes to RNA?
Transcription
What are 3 base pairs of RNA called?
A codon
How many different possible codons on there?
64
What is the strand without Okazaki fragments called?
Leading strand
What is the stand with Okazaki fragments called?
The lagging string
What is the purpose of genetic material?
Creating rotting
What will you have after transcription?
Single stranded mRNA
What is the difference between the coding strand & mRNA?
Thymine is replaced b uracil
What direction is mRNA translated?
5’ →3’
What direction will the protein sequence /peptide be made in?
N’ →c’
What binds to the mRNA during translation?
Ribosomes which tRNA binds to
How do you know which is the template strand & which is the coding strand of DNA?
Template goes 3’ →5’ & cooding goes 5’ →3’
What is a wobble position?
The 3rd position on mRNA, not as important as the fist two positions
What decides which amino acid is formed?
The fist 2 positions of a nucleotide, ex: tac t &a decide
Where is the mRNA released into?
The cytoplasm
What can correct error not caught by the replication machinery when it comes to DNA?
Mismatch repair
What protects mRNA from being degraded by our exonucleases in the cytoplasm?
The 5’ end which has 3 phosphates connected to 2 5’
How is mRNA terminated?
Rho protein goes up to RNA polymerase where it cleaves the mRNA & makes the 3’ end poly a (polyadenalation)
What is attached to t 3’ mRNA to prevent exonuclease activity?
Polyaderalation to which 100-200 adenine bases an connected
What happens during mRNA splicing & what performs it?
It is performed by splicesomes, introns are made into loops & cut away, connecting the exons
What is an important part of gene expression?
Splicing
When do transcription & translation happen in prokaryotes & why in that order?
The happy simultaneously due to there being no nucleus
What is the starting codon in mRNA? & what enzyme does it code for?
Aug, methionine
Where do the enzymes bind in prokaryotes mRNA before it starts translation?
The shive delgarno sequence
Where does binding of enzymes occur in eukaryotes when mRNA is to be translated?
The 5’ cap
Are all the Aug codons the start codon for eukaryotes?
No, only the one that is part of the Kozak consensus sequence
What are the 2 units of ribosomes?
The small ribosomal subunit & the large ribosomal sub unit
What does the small ribosomal subunit do?
Attaches to the 5’ cap & starts scanning until it finds the Aug start codon
How does smooth er become rough er?
When the ribosomes which are translating the mRNA bind to it due to the signal recognition particle attached to the ribosomes
What does smooth er produce?
Lipids
What does rough er produce?
Proteins
What are the 3 processes that creates the central dogma of biology & makes DNA → RNA → protein?
DNA replication → transcription → translation
Where does DNA replication occur?
Where there is DNA, nucleus & mitochondrial matrix & chloroplast stroma of plant cells
What direction do all DNA processes occur in?
5’ → 3’
During what phase does DNA replication occur?
S-phase
Where in the cell does transcription occur?
Where there is DNA, nucleus & mitochondrial matrix & chloroplast stroma of plant cells
What produces mRNA?
RNA polymerase ll
What is rRNA & what is it used for?
Ribosomal RNA. RNA used with ribosomal proteins to form ribosomes
What produces rRNA?
RNA polymerase l
What is tRNA & what is it used for?
Transfer RNA which is used to ferry amino acids to the ribosome during translation
What produces tRNA?
RNA polymerase lll
Where does pre-mrna processing take place?
Only nucleus
What are introns & exons?
Regions of mRNA
What is expressed, introns or exons?
Exons
What is the poly A tail?
Multiple adenines added to 3’ end
What is mRNA converted into during translation?
Polypeptide
What happens to polypeptides after translation?
They are modified into proteins
Where does translation take place?
Cytosol, mitochondrial matrix & chloroplast stroma
What are the 3 sites in the large ribosomal subunit called?
E,p, A
What is the significance of Aug & what amino acid does it code for?
Start codon, codes for methionine
What does anti codons bind to?
mRNA
What bonds are formed during transcription?
Covalent bonds & phosphodiester bonds
Where do the activities of the central dogma take place in prokaryotes?
The cytosol
What part of the central dogma is cut out of the process in prokayotes?
The modification of the mRNA does not take place as it is being translated simultaneously (they a coupled)
When does dna replication occur in prokaryotes?
The first step during binary fission
Where is replication slower, eukaryotes or prokaryotes?
Eukaryotes
How many origins of replication are there in eukaryotes and prokaryotes?
Multiple origins in eukaryotes & single origin in prokaryote
How many types of RNA polymerase are there in eukaryotes vs prokaryotes?
3&1
Does mRNA in prokaryotes have introns?
No
How many proteins can mRNA code for in eukaryotes vs prokaryotes?
One ( the mRNA is monocistronic) & many (the mRNA is polycistronic )
What kinds of ribosomes do eukaryotic & prokaryotic cells have?
80s/ 70s & only 70s
How should you think about mitochondria & chloroplast?
As a prokaryote
What kind of structure is the nucleoid of a prokaryote?
Circular, dose strands single chromosome
How does the nucleoid of a prokaryote look?
It is supercoiled
How is DNA organized in eukaryotes?
Decondensed
Main difference between eukaryotic & prokaryotic chromosomes
There are many in eukaryotes where there is only a single double stranded in prokaryotes
What is pleiotropy?
When one gene affects multiple charactaristres
What are recessive lethal alleles?
Alleles which can be lethal (when homozygous)
What and dominant lethal alleles?
Alleles that cause death even when only one copy is present
What is polygenic traits/inheritance
When many alleles contribute to the same trait such as height
Which kind of cell has on average more genes & chromosomes?
Eukaryotes
What is the most common kind of gene regulation?
Transcription initiation
What is the preferred source of nutrient for prokaryotes & what can it be substituted with?
Glucose is preferred, can be subbed w/ lactose
What are operons? (Prokaryotes)
Genetic regulatory systems
What are the 3 components of the DNA sequence of an operon? (prokaryotes)
Promoter, operator and genes which each code for a protein
What controls gene regulation in bacteria?
Bacteria is a prokaryote thus operons controls gene regulation
What are constitutive genes?
Always expressed, vital for function
What are facultative genes?
Genes expressed based on environment
What does it mean that an operon is inducible? ( prokaryotic gene regulation)
Off by default but It can be turned on by the precense of a particular small molecule
What does it mean that an operon is repressible? ( prokaryotic gene regulation)
It is on by default but can be turned off by a small molecule
What does gene regulation allow for? ( prokaryotic gene regulation)
It allows for bacteria/the cell to respond to changes in environment by altering gene expression
When does e. coli express the lac operon? What 2 conditions
Lactose is available & glucose is not
What senses the precense of lactose in the lac operon?
The lac repressor
What senses the precense of glucose in the lac operon?
The catobolite activator protein (cap)
Why is the metabolism of glucose preferred to that of lactose?
It takes less energy
What makes cell different? (They all contain the same “building blocks”
Gene regulation
What are transcription factors?( gene regulation)
Protein that help turn a specific gene on or off by binding to DNA
What are other types of gene regulation aside from transcription initiation? (eukaryotes)
Alternative splicing, targeting by MicroRNA, protein activity regulation through removal of amino acids or addition of chemical groups
Dominant autosomal linked inheritance / diseases
Free earlobes, achondroplasia → dwarfism, early balding (m), curly hair, progeria → premature aging, dactyly → digits, huntington
Recessive autosomal linked inheritance / diseases
Albinoism, attached earlobes, cystic fibrosis, sickle cell disease, tay-sachs disease
What are autosomal linked diseases?
Genetic diseases relating to one of the 22 non sex chromosomes
What ar x- linked diseases?
Genetic diseases linked to the x- chromosome
What is ploidy / non disjunction and where does it occur?
Addition or loss of chromosomes due to uneven split of chromosomes in meiosis I
When does misdivision happen & what is it?
Meiosis ll, uneven split between chromosomes
Is it possible to have a child with no x-chromosome
No, if the egg is fertalized & there only is a Y chromosome it is not viable
What syndrome is caused when a female child only has 1 X chromosome?
Turner syndrome
What syndrome occurs when a baby is born with xxy chromosomes?
Kleinfelter syndrome
What syndrome occurs when a baby is born with XXX chromosomes?
Triple x syndrome, the female is normal
What does pcr mean?
Polymerase chain reaction
What is the product of PCR?
Multiplication of the target DNA
What are DNA vectors? ( gene cloning Via bacteria)
DNA molecules that act as vehicles to allow genes & other DNA sequences of interest to be stored, manipulated o introduced into other organisms
What is the most common type of vector? (Gene cloning )
Bacterial plasmid
What at the 4 types of vectors?
Plasmids - most commonly used
Viral vectors
cosmids
Artificial chromosomes
What is reverse transscription?
RNA → DNA
What is the machinery associated with HIV?
Contains Reverse transcriptase enzyme used to make complementary DNA from its RNA genome
How does DNA cloning work?
DNA fragment is inserted into a circular DNA molecule called a plasmid. The plasmid is replicated in bacteria calling many copies of the gene in interest
Definition of DNA cloning
Identical copies of piece of DNA
How are genes to be cloned cut out?
Using restriction enzymes
What is used to connect the DNA to the plasmid in DNA cloning?
DNA Ligase ( type of enzyme)
What is used to make the bacteria take up plasmid when DNA cloning?
Typically a heat shock, a shock to the system is needed
What is placed in the plasmid along with the DNA of interest to make it clear which bacteria has obtained the plasmid? (DNA cloning )
Gene for antibiotics resistance is put in the plasmid so when the bacteria is put in nutrients a antibiotics only the bacteria with the plasmid survives
What is the process called in which bacteria can take up foreign DNA?
Transformation
What is the first step in pcr?
Separating the DNA strands. Process is called denaturation & uses heat to break up the hydrogen bonds a separate the strands (96 c )
What is the polymerase used in pcr called & why that one?
Taq polymerase, needs to be heat resistant as the “cool” part of the process is 55c
What is gel electrophoresis used to?
Measure length of DNA
What is a palindromic sequence?
Sequence of DNA that is the same on top & bottom, Google picture
How do restriction enzymes work?
The recognise palindromic sequences & cuts it leaving “sticky ends”, google pictures
They open up the circular DNA
What is used to connect the DNA strands in DNA cloning? (hint : it is an enzyme)
Ligase
How many copies of DNA do you get when replicating DNA during pcr?
2 for each cycle so total number =2^n where n is number of cycles
What is needed for pcr?
Target DNA, taq polymerase, DNA nucleotides & primers
What is Southern blotting?
DNA separated in gel electrophoresis
What is northern blotting?
RNA separated in gel electrophoresis
Would you look at DNA or RNA if you want to study gene expression?
RNA
During what phase do organelles (aside from nucleus) duplicate?
Interphase, G1
How many percent of the cell cycle does mitosis make up?
10%
How many percent of the cell cycle does interphase make up?
90%
What does the frequency of mitosis depend on
Cell type
Do all cells undergo mitosis?
No
Example of cells that don’t undergo mitosis & what is their phase called?
Red blood cells, G0
What is cytokinesis?
Duplication of the cytoplasm
What are the only type of cells that undertake meiosis?
Gamete forming cells (spermatocytes & primary oocytes )
What do you get at the end of meiosis?
4 haploid sperm & egg cells, all different
What is karyotype?
The complete set of chromosomes in a species cell
How are karyotypes ordered?
In homologous pairs, by size & centromere location
Benefits of ordering karyotypes
Allows for analysing chromosomes & identify abnormalities
Visible difference between X & y chromosome?
Size, x is bigger
How do you obtain the karyotype? ( 4 steps)
Sample: blood, amniotic fluid, tissue etc, just need cells
Metaphase arrest: cell cycl halted at metaphase
Chromosome staining & analysis
Karyotype interpretation
What does chromosome numbers denote?
The pair, so chromosome 4 is the 4th pair
How do you denote a healthy diploid karyotype for a female?
46,xx
How do you denote a healthy diploid karyotype for a male?
46,xy
How do you denote karyotype for a female with trisomy?
47, xx +number of effected chromosome
How do you denote karyotype for a male with trisomy?
47, Xy+ number of the effected chromosome
Which chromosome is there an extra copy of in downs syndrome?
21
Example of trisomy
Downs syndrome
How do you denote karyotype for a female with monosomy?
45,xx-number of effected chromosome
How do you denote karyotype for a male with monosomy?
45, xy- * number of effected chromosome*
What does the haploid number (n) denote?
Number of distinct chromosome pairs
What is the haploid number for humans?
23
What is ploidy?
Number of sets of chromosomes, humans have 2 sets as chromosomes are paired together
Which cells are haploid?
Gametes
Which cells are diploid?
Somatic cells
What does it mean that a cell is anucleate? Example
No chromosomes, erythrocytes
What is polyploidy?
When the organism has more than 2 complete sets of chromosomes
Where is polyploidy normal & common?
Certain species, common in plants
What is aneuploidy?
Abnormal number of chromosomes, not every pair is effected (example, trisomy)
What is nullisomy?
When an entire chromosome pair is missing
Is aneuploidy ever normal?
No
Where are operons found?
Prokaryotes
Mnemonic to remember components of an operon
Prog
Promoter
Repressor
Operator
Genes
What does the lac operon regulate?
Ability to consume lactose
What do lactose / allolactose do to the repressor of a lac operon & what are they called?
Removes the repressor, it’s called an inducer
How many genes are in the lac operon and what do they do?
3, they produce proteins that help the prokaryote consume lactose
What does the trp open regulate?
The ability to produce tryptophan
What is tryptophan & who needs it? Where can you get it from
Amino acid, us & bacteria
Diet if possible otherwise made it using trp operon
How many genes in the trp operon?
5
What happens to the trp operon if tryptophan is available?
Tryptophan binds to oppressor & oppressor binds to operator & stops production
What is the corepressor of Trp operon?
Tryptophan
What is myosin?
The thick filament of the sacomere
What is the structure of actin?
Does one cell division in mitosis lead to an immediate increase or decrease in mass?
Decrease
What bonds are between RNA primer & its Okazaki fragments?
Covalent bonds
How are mitochondrial genes transmitted to offspring?
Maternally (from mom )
