Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Bio unit 3
Exam revision
| Question | Answer |
|---|---|
| what is gene expression? | the process which converts the DNA information into the structures and functions of a cell. - A gene is expressed through translation and transcription - genes can be ‘turned on’ or ‘turned off’ this is gene expression |
| what is variation? | phenotypes are influenced by genotype and environmental factors. - variation is the diversity of genetic and phenotypic traits within/between populations - driven by; environmental factors, mutations, sexual reproduction |
| what environmental factors and how do they effect gene expression? | phenotype is influenced by genotype, can also be influenced by external factors. - genotype is not changed by environmental factors, but environmental factors can turn allele variation on/off e.g. temperature, Light, pH, availability of food or light |
| differential gene expression, explain? | cells carry the same genes but not all cells express the same genes. - depending on the cell’s specialist functions the genes are expressed accordingly - leads to specialisation |
| what is phenotypic variation? | variation that occurs within a species due to the expression of different alleles. - alleles are alternate variations of a gene - Maternal chromosome can carry the same or different variations of an allele as a paternal chromosome |
| what are some examples of environmental factors that effect gene expression in different organisms? | temperature - tipping on Himalayan rabbit (where the rabbit experiences the cold turns black) light -butterflies in different colours lights change wing colour/size. pH- Hydrangea flower colour change, pink high pH blue low pH |
| how is genetic variation maintained during meiosis? | meiosis-a chromosome from each parent crossing over-swapping of alleles in a gene to combine traits random assortment-any homologous chromosome either side before anaphase Fertilisation - combination 2 sets of chromosomes mutations - new DNA |
| what is a pedigree chart? | pedigree charts are used to show inheritance of a trait or disease. - they are ordered in generations and show offspring, partners+ children - ordered via codes (II 2) - each symbol in a pedigree has different meanings |
| how does mutation increase variation within a population? | mutations provides allelic variation - It is an ultimate source of genetic variation - foundation of evolutionary change Essentially allows ne versions of DNA to be created |
| how are pedigree charts used to determine patterns and the probability of inheritance? | pedigree charts can be used to determine the characteristics and probability of inheritance can be seen though the examination of a pedigree. |
| what is a mutation? | a permanent structural change in the DNA -changes the genetic material and changes the nucleotide sequence of DNA -also provided allelic variation and is the source of genetic variation and the foundation for evolutionary change. |
| what is meant by the effect on phenotype in regards to mutation? | Effects can be -neutral – no effect -deleterious- negative effect -beneficial- evolutionary advantage Can affect: -somatic cells- condition is only in the individual cell -genetic- in germline cells, offspring can inherit |
| what are mutagens? | environmental agents that cause mutation. e.g. -chemical= alcohol, char in tobacco, irritants/poisons -biological- virus/pathogens -physical-ionising radiation/UV |
| what is meant by the “amount of genetic material altered” in regards to mutation? | point mutation ^ nucleotide sequenc Chromosome mutation chunks of chromosomes are affected delete- section of chromo gone Inverted- section falls, reattaches wrong way Duplicated -chromo + Translocated- bit of chromosome falls, fuse to diff chromo |
| what is meant by the origin of mutation regarding mutation? | -spontaneous: error in DNA replication -Induced: caused by mutagens |
| What is a point mutation? | is where a single nucleotide within the original DNA sequence is affected by; -substitution: when one nucleotide is replaced by another -deletion: the loss of one or more nucleotides -addition: the addition of one or more nucleotides within a gene |
| what is chromosome mutation? | whole changes to a chromosome, and not just one single gene -can affect multiple genes at the same time -parts of the chromosome may be Deleted Duplicated Rearranged Attached |
| what is inheritance? | the passing og traits from parents to offspring -certain genes dominate the expression of some traits e.g. blood type (A and B are dominant over O) |
| what is Mendel’s fist law? | Law of segregation alleles separate during gamete formation, and randomly unite at fertilisation Assumptions that must be made: - there are alleles - inherit 2 alleles - during meiosis alleles separate leaving 1 - there is dom and rec alleles |
| what is non-disjunction and aneuploidy? | Non-Disj=is when during anaphase stage of meiosis 1 or II, the chromosomes don’t move equally to opposite sides of the cell (poles) Aneu= is a type of non-disjunction where the is a +/- of a single chromosome |
| define the terms: Genotype Phenotype monohybrid | Genotype- specific combination og genes that determine a characteristic, and whether its expressed or not. Phenotype- the physical expression of the trait- what is looks like Monohybrid- heterozygous organism with respect to a single autosomal gene |
| what is a monohybrid cross? | inheritance if a single autosomal gene - relates to Mendel’s observation of the ratio of 3:1 in the f2 generation - only have 1 gene investigated - punnet square can be used to investigate a monohybrid cross |
| what is a dihybrid cross? | involves 2 genes with two different alleles for each gene. Inheritance of 2 genes at a time -done with a 4x4 punnet square Ratio is 9:3:3:1 - there can be 4 different variations of offspring phenotypes |
| what is polygenetic inheritance? | a single characteristic can be controlled by more than one gene -polyenes are genes that have a small addictive effect on phenotype - Large number of allele combination possible - show continuous variation e.g. height |
| what are test cross’ used for? | used to determine whether an offspring is homozygous or heterozygous if their genotype is unknown but has a dominant phenotype. 50 dom/50 rec= heterozygous parents 100% dom offspring= homo parents |
| what is Mendel’s second law? | law of independent assortment “the inheritance patter of one trait will not affect the inheritance pattern of another” -this happens when the genes that are concerned are on different chromosomes |
| define the terms. Complete dominance Incomplete dominance codominance | Complete dominance-dominant allele expressed in offspring and hides recessive allele. Incomplete dominance- both alleles partially show by blending. Codominance- both alleles are fully expressed at the same time |
| what is an example of multiple alleles? | BLOOD GROUPS -3 alleles (A B 0) -A/B dominant over O -A/B codominant Possible phenotypes -A, B, AB, O (recessive) |
| Define evolution | the process of cumulative, gradual, inheritable change in a population of organisms that occurs over many generations and a relatively long time. |
| Define Natural selection | Occurs when selection pressures confer a selective advantage on a specific phenotype. Individuals with certain traits are more likely to survive & reproduce at a higher rate. Can cause changes in a population allele frequency, causing evolution. |
| Define common ancestor | An ancestor that is shared by different species. |
| What is evolution driven by? | Natural selection and this is proven through common ancestors. |
| What is biogeography? | Biogeography studies the distribution of species of plants and animals throughout the world over time. This is done by mapping the fossils This evidence for evolution as it displays species that evolved from a common ancestor. |
| comparison of genome sequence? | The similarity in genome referred to as homologous genes, The shared features of genetic material, similar genetic codes and process of gene expression alludes to the fact that all organisms are related and evolved from a common ancestor |
| DNA hybridiseation | the combination of two species DNA to prove genetic relatedness the DNA is heated up and then mixed through heating similar sequences will bind to each other and sequences that are dis similar will remain separate |
| what is binary fission? | Asexual prokaryotic gene reproduction 1 circular chromosome with no centromere 1. prior chromosome slightly coiled 2. DNA replicate 3. attaches to cell wall during elongation 4. cleavage furrow begin to form 5. cell wall develop 6. DNA recoils |
| what is the process mitosis? | prophase nuclear membrane gone nucleolus gone spindle fibres form centrosomes move to pole metaphase chromosome on equator Anaphase spindle fibre separate chromatid telophase nuclear membranes form spindle fibre gone cleavage furrow cytokinesis |
| what are the stages in Meiosis I? | prophase1 centrioles to poles, homologous chromosomes metaphase1 homologous pair on equator crossing over indi assort Anaphase1 homologous pair separates telophase/cytokinesis1 cleavage furrow, 2 haploid cells form, still consists of 2 sis chromatids |
| what are the stages in meiosis II? | prophase2 new spindle fibres no nuclear membrane metaphase2 line single file on equator, spindle fibres attach Anaphase2 sis chromatids separate telophase/cytokinesis2 cleavage furrow 4 haploid nonidentical daughter cells form |
| what is the DNA structure? | made of nucleotides sugar phosphate back bone(Deoxyribose)phosphodiester bonds, with nitrogen base cytosine-guanine thymine-adenine hydrogen bonds, breakable for replication nucleotides bond to each other to form DNA running 5-3 the other 3-5 |
| how is DNA different in prokaryotes and eukaryotes? | prokaryotes: unbound circular DNA in the cytosol, plasmids, no histones, reproduction binary fission Eukaryotes: linear DNA in nucleus chloroplasts/mitochondria, bound in by membrane, no plasmids, membrane bound organelles, reproduction meiosis mitosis |
| what is protein synthesis? | involves transcription and translation transcription is where a gene's sequence is copied to by discrete sections to be transported out of the nucleus-messenger RNA or mRNA translation is where ribosomes translate the mRNA into proteins |
| describe transcription? | 1RNA polymerase binds to gene 2unwind 3RNA polymerase form mRNA adding nucleotide in 5-3 (complementary) 4pre mRNA is release DNA rewind 5mRNA modified methylated cap added to 5 poly-A tail is added to 3 6introns removed 7leaves nuclear pores |
| describe Translation? | 1mRNA attaches to ribosome 2ribosome moves from start codon AUG making protein 3 each codon there is Anticodon tRNA that brings AA 4AA join by peptide bond polypeptide chain 5Once tRNA has delivered it dethatch 6stop codon it folded into protein |
| what is noncoding DNA? | Noncoding DNA are introns located withing genes removed when making proteins not found in mRNA |
| what is coding DNA ? | exons genes that encode for proteins |
| what is a base triplet? | codons group of 3 nitrogenous bases that code for an amino acid |
| what is histone modification and DNA methylation? | histone mod is the addition of a chemical group that regulates the transcription of DNA. DNA methylation is where a methyl group is added to DNA and controls gene expression |
| what is DNA profiling? | the unique repetition of STRs in DNA Isolate- DNA cut by restriction enzymes Replicate- PCR Measure- Gel electrophoresis inspect- DNA under UV light |
| What is the process of PCR? | makes copies of DNA for analysis components: sample, primers, nucleotides, taq polymerase method denaturing: 95C separates the strand Annealing: 50-60C allows primers to join comp sequences at opp ends Extension: 75C taq polymerase adds new strand |
| What is gel electrophoresis? | 1cut by restriction enzyme 2 agarose gel with wells covered with buffer 3 DNA added 4 electric current 5 - DNA moves to + terminal 6 sml strands move more easily through gel/ travel further |
| what is an STR/microsatellite ? | repetion of bases 3 or more times in a row this is part on the introns and is a highly variable portion of DNA |
| what is a restriction enzyme? | cuts DNA at specific points 4-8 pairs in length [palindrome] can be blunt ends- universal sticky ends - specific, must be cut with the same enzyme |
| what is recombinant DNA? | combining 2 organism's DNA fragments - genetically modified organism done 3 ways 1 using plasmid 2 restriction enzyme 3 gene cloning |
| what is gene cloning? | creating a bacterial vector 1 recombinant plasmid introduced back into bacteria 2 once successfully transferred to bacteria it is said to be transformed 3 this is replicated naturally causing mor copies |
| how is recombinant DNA created using restriction enzymes? | 1 gene is cut and vector is cut 2 gene fragment and plasmid are combined 3 DNA ligase seals |
| how is recombinant DNA created using plasmids? | using circular DNA from bacteria can be used as an alternative of PCR |
| what are viral vectors? | infect cells by injecting their DNA into the cells- this tecnique can be used to inject recombinant DNA into a virus' DNA or RNA can be used to create vaccines |
| how can transgenic organisms be used? | medicine agriculture- improving nutrition, yield etc. |
| what is comparative bio chemistry? | through the analysis of proteins and amino acid sequences cell machinery evolution can be proven |
| what is embryology? | the study and comparison of embryo development across species. embryos can show shared feature not present in adults, this can display relationships. e.g. vertebrate embryos all have gill slits, tails and limb buds |
| what are homologous structures? | are anatomical features that are common in more than one species but may not be used in the same way. they are said to follow the same plan. they may have been passed on from a common ancestor |
| what is fossilisation and the fossil record? | the creature must die and then be rapidly buried in low oxygen environment. only the hard body parts are fossilised. the fossil record is limited and misses morphological species, it is subject to scientific opinion. |
| why are mutations the ultimate source of genetic variation? | they are changes in DNA and can have large effects. evolutionary change can be as a result of the accumulation of many mutations. |
| what is gene flow? | movement of genes from one population to another when individuals or genetic information disperses between the two populations. This causes allele frequency to increase |
| what is genetic drift? | the random fluctuation in allele frequency of alleles within a population over generations * occurs due to chance |
| what is the founder effect? | small populations migrate away from parent pop and become isolated. individuals may not carry alleles from the gene pool. this decrease genetic diversity. deleterious genes may become more common. |
| what is artificial selection? | the intentional breeding of individuals with desired traits resulting in a change in allele frequency. requires human intervention. the traits are beneficial to humans. |
| what is speciation? | the process by which new species arise from existing species. occurs in populations when a species becomes reproductively isolated from one another. they can no longer breed to produce fertile offspring. |
| what is allopatric speciation? | speciation due to a population become physically isolated from one another through geographical isolation |
| what is sympatric speciation? | evolution of two species from a population in the same place with no geographical isolation. isolating mechanisms = reproductive isolation. prezygotic isolation may breed at different times etc. post reproductive mech mating but no viable offspring |
| what are macro evolutionary changes? | the accumulation of micro evolutionary changes. results in speciation |
| what are micro evolutionary changes? | small changes in the genetic composition of a pop over generations. leads to variation with in species. |
| what is convergent evolution? | when organisms evolve similarly to their environment whilst being completely unrelated. These features come about due to similar selection pressures. |
| what is divergent evolution? | where groups of organisms acquire more and more differences leading to speciation. This is usually as a result of segregation, this causes the different populations to adapt to the new environment and decreases gene flow between the populations. |
| what is sanger sequencing? | 1 the double stranded DNA is denatured 2 a primer is added to one end of the sequence 3 polymerase adds dNTPs and only one ddNTP is added 4 DNA synthesis until ddNTP strand termination 5 the DNA fragments are denatured 6 Gel electrophoresis |
Created by:
Florinda?
Popular Biology sets