Mod 5 Heredity Flashcards

Question

What is a positive feedback loop?

Answer 1

stimulatory effect

Answer 2

inhibitory effect

Answer 3

triggers pituitary to release FSH and LH

Answer 4

* stimulates follicle growth * stimulates oestrogen secretion from developing follicles

Answer 5

* surge causes ovulation * results in formation of corpus luteum

Answer 6

inner cell mass

Answer 7

trophoblast cells

Answer 8

Prophase I

Answer 9

Diploid cell: 1. Interphase - cell grows, DNA replicates, cell grows again 2. Prophase I - crossing over, chromosomes find homologous pairs, centrosomes move to opposite ends of cell and spindles begin to form, nucleus breaks down 3. Metaphase I - nucleus disappears, chromosomes line up in homologus pairs along middle of cell, spindle fibres help with this 4. Anaphase I - spindle fibres pull homologous pairs apart 5. Telophase I - cleavage furrow, nuclear membrane re-forms 6. Cytokinesis I - cell membrane divides and reforms 7. Prophase II - no crossing over, centrosomes replicate, centrosomes move to opposite ends of cell, nucleus breaks down 8. Metaphase II - chromosomes line up along middle of cell, no homologous pairs, nucleus disappears 9. Anaphase II - sister chromatids pulled apart by spindle fibres 10. Telophase II - cleavage furrow, nucleus re-forms Haploid: 11. Cytokinesis II - cell membrane divides and reforms to form 4 haploid gametes

Answer 10

1. Interphase - cell grows, DNA replicates, cell grows again 2. Prophase - centrosomes move to opposite ends of cell and spindles begin to form, nucleus breaks down 3. Metaphase - nucleus disappears, chromosomes line up in single file along middle of cell, spindle fibres help with this 4. Anaphase - spindle fibres pull sister chromatids apart 5. Telophase - cleavage furrow, nuclear membrane re-forms 6. Cytokinesis - cell membrane divides and reforms, 2 diploid cells

Answer 11

**Initiation** * DS DNA unwinds * Helicase 'unzips' DS DNA by breaking hydrogen bonds between BPs * creates a replication fork as each strand acts as a template for replication **Elongation** * DNA Polymerase adds free floating nucleotides by complementary base pairing * Lagging strand is synthesised in opposite direction to the action of Helicase * Leading strand is synthesised in the same direction to the action of Helicase - continuous synthesis * BOTH STRANDS HAVE A LEADING AND LAGGING STRAND * All strands synthesised 5'-3' * Ligase joins adjacent Okazaki fragments (by recreating phosphodiester bonds) **Termination** * Semi-conservative replication has occured (half parental strand half newly synthesised) SS = Single stranded BP = base pair | DS = Double stranded

Answer 12

**Similarities:** * Double helical structure * A, C, T, G * A-T, C-G * Code for proteins * Have extranuclear DNA **Differences:** * Prokaryote - circular, Eukaryote - Linear * Prokaryote - no histone, Eukaryote - folded around histone * Prokaryote - smaller genome, Eukaryote - Larger genome * Prokaryote - less folded, Eukaryote - highly folded * Prokaryote - nucleoid region, Eukaryote - nuclear membrane * Prokaryote - RNA has only exons, Eukarytoe - RNA has introns and exons * Prokaryote - Extranuclear DNA in plasmids, Eukaruote - extranuclear DNA in mitochondria * Prokaryote - transcription & translation happen simultaneously, Eukaryote - transcription & translation happen separately

Answer 13

* Adenine and Guanine * double ring

Answer 14

* Cytosine and Thymine * Single ring

Answer 15

* expressed segment of DNA * translated into an amino acid * mature RNA is only exons

Answer 16

* Segments of DNA that do not code for an amino acid * They may turn off/on a gene * Intervening sequences that are removed (spliced) prior to translation during **post-transcriptional modification** * 98% of human DNA

Answer 17

* DS DNA unwinds * Helicase 'unzips' DS DNA by breaking hydrogen bonds between BPs * creates a replication fork * **one** strand is used as template for RNA * RNA polymerase adds free floating nucleotides to template (A, C, **U**, G) by complementary base pairing * synthesised 5'-3' * Introns are spliced * mature mRNA exits nucleus and enters cytoplasm (ribosome)

Answer 18

* mature mRNA enters ribosome * ribosome reads mRNA in triplet codons * tRNA bonds to codon by complementary base pairing of anticodon site * tRNA places amino acid in polypeptide chain * tRNA detaches

Answer 19

ICSFEB - Iguanas can't speak from eating brocolli * **i**nheritance & continuity of species depends on it * results in production of **c**omponents necessary for protein formation * proteins are vital to the **s**tructure & **f**unctioning of cells * allows for inherited qualities encoded by DNA to be mobilised into cellular structures & function - allowing **e**xpression of the genes * functional, active proteins involve numerous **b**iochemical processes that must be co-ordinated to prevent death of organism, cell death, or disease

Answer 20

* **Growth** - making new cells, organism gets larger, mitosis (nuclear division & cytokinesis), cell differentiation * **Repair** - apoptosis (cell death) of sick cells, replacement of dead/worn out cells to repair damaged tissue * **Reproduction** - meiosis (sexual, genetic variation) and mitosis (asexual, no variation) * **DNA replication & Cell replication** * Reach **sexual maturity** - zygote → adult → produce gametes/reproduce * Need **genetic variation** for environment (natural selection) to act on in times of change (evolution) * Genetic variation created by mutation, meiosis (independent assortment, crossing over, random segregation), random fusion of gametes (fertilisation)

Answer 21

* important that mRNA copies the correct complementary nucleotide to the template strand to get the right amino acid * mRNA is important to carry the genetic information outside the nucleus to be translated and turned into a protein * important that tRNA complementary base pairs to codon to bring the correct amino acid * important that polypeptide chain is correct to fold correctly and make a functional protein

Answer 22

* UV exposure - more UV rays leads to more melanin & darker skin/freckled phenotype * Nutrition - amount of nutrition affects height expressed * Herbivory - can 'switch on' gene for serrated leaves in holly * pH - hydrangea colours change to blue/pink depending on soil acidity

Answer 23

* carrying substances across membranes or around the body * transport and store oxygen in blood * help molecules move in/out of cells in cell membranes * haemoglobin - binds oxygen & carries it through the blood, delivering to cell

Answer 24

* singal molecules to control biological processes & coordinate responses in cells, tissues, and organs * oestrogen - regulates menstrual cycle & maintains pregnancy

Answer 25

* provide physical support or protection * strong, fibrous, and stringy * collagen - found in skin, connective tissue, and bones

Answer 26

* antibodies (immunoglobins) that protect the body by identifying and killing disease-causing organisms * Immunoglobin A - destroys disease-causing organisms growing in the gut and airways

Answer 27

* enzymes that increase the rate of chemical reactions without being used/changed in the reaction * Amlyase - breaks down starch into sugars

Answer 28

* contracile proteins involved in muscle movement and internal supporting structures of cells * Actin & myosin - work together to bring movement in all the muscles of the body

Answer 29

quaternary

Answer 30

**DNA** * macromolecule made of a DS of nucleotides held together by weak hydrogen bonds between BPs * double helix * deoxyribose sugar **nDNA** * DNA arranged as chromosomes in the nucleus **mtDNA** * small molecules of DNA in mitochondria * extra-chromomosal/non-nuclear DNA

Answer 31

**RNA** * SS molecule of nucleotides * ribose sugar * A, C, U, G **mRNA** * messenger RNA * SS complementary to DNA sequence of template strand * each triplet codon codes for specific amino acid * transfers genetic code from nucleus to ribosome in cytoplasm **tRNA** * transfer RNA * clover-lead shaped, short segment of RNA * carries a specific amino acid on one end, determined by the anticodon at the other **rRNA** * ribosomal RNA * forms ribosome subunits

Answer 32

most amindo acids can be coded by more than one codon

Answer 33

different versions of the same gene

Answer 34

the pair of alleles an individual inherits for a characteristic

Answer 35

* dominant allele is not completely dominant over recessive allele * blend of recessive and dominant allele * e.g. pink flower colour coming from red and white flower

Answer 36

* both alleles are expressed separately * e.g. roan cows - brown and white spots on coat

Answer 37

* if X chromosmoe has a recessive gene, the male will be affected as there is no corresponding dominant gene to cancel it out * these recessive traits disproportionately affect males * passed from female → male → female * male cannot pass to male as they would only pass on their Y chromosome (does not have allele)

Answer 38

* traits carried on sex chromosomes (X or Y) * Hemizygous chromosomes - there is no corresponding locus on Y chromosome for traits on X chromosome

Answer 39

* More than 2 versions of an allele in a gene pool * results in 4 or more possible phentoypes * e.g. A, B and O blood groups

Answer 40

* Can be passed from only male parent → male or only female parent → female * If dominant X-linked, two unaffected parents cannot have an affected child & two affected parents can only have unaffected son * If recessive X-linked, two unaffected parents can only have an affected son & two affected parents cannot have an unaffected child

Answer 41

* two affected recessive parents cannot have an unaffected offspring - must be dominant AND heterozygous parents * 100% incidence of affected daughters from father **suggests** X-linked dominance - dominant affected father & recessive unaffected mother will produce all affected daughters and no affected sons (daughters must inherit dominant X from father and will be affected)

Answer 42

* if dominant, two unaffected parents cannot have an affected offspring - must be recessive autosomal, parents must be heterozygous * 100% incidence of affected sons from an affected mother suggests X-linked recessive - dominant unaffected father & recessive affected mother will produce all unaffected daughters and all affected sons (sons will not get dominance from father as they have to get the Y)

Answer 43

male → female → male → female pattern **suggests** X-linked but cannot be confirmed

Answer 44

Selective breeding * we can create organisms with desirable traits to produce higher quantity and quality of agricultural products * increases income and yield * foods can be made less resistant to pests - farmers use less pesticides & spend less money - better for environment * reduces biodiversity & reduces gene pool - may hinder organism survival if affected by a specific disease

Answer 45

Natural breeding * farmers place male and female in same encolsed environment and wait for them to breed * very common and cheap * takes a long time Artificial Insemination * sperm is taken from male with desirable traits and inserted into female * Cheap & decreases risk of STDs * Decreases genetic diversity Artificial Pollination * person takes pollen from one flower and places it directly into another flower * Increases size, quantity, and seed numbers of fruit * Inefficient and costly Cloning * Can be whole-organism or gene cloning * not widely used * can increase yield and clone desired traits * decreases genetic diversity

Answer 46

* Single Nucleotide polymorphism * when a single nucleotide (one base pair) is incorrectly inserted during DNA replication * mutation at a particular location on a chromosome * must be present in at least 1% of population * most SNPs occur in introns and do not cause any observable differences

Answer 47

A set of SNPs that tend to be inherited together as they are physically close on the same chromosome

Answer 48

* selected SNPs that represent a whole haplotype * instead of looking at every SNP in a haplotype, scientists can study just the tag SNPs and still infer the presence of the others

Answer 49

* crossing over can unlink SNPs from their associated genes * this reduces their utility as genetic markers * to account for this, multiple SNPs associated with one gene are studied * single SNPs cannot confirm disease - multiple are required

Answer 50

* Some sets of adjacent SNPs - haplotypes - are associated with a phenotypic change * E.g. change in appearance, enzyme functioning, disease susceptability, response to drugs * can be used to identify genetic disease in individuals, infer patient responses to medicines, and prenatal paternity tests * faster than using whole genome

Answer 51

* Using genome wide association studies (GWAS) * studies entire set of DNA from a large group of people to identify SNPs

Answer 52

* You inherit one version of each SNP from each parent at the same locus * almost every SNP has a corresponding SNP at the same locus on a homologous chromosome

Answer 53

* a technique by which individuals can be identified via their DNA profiles * uses the non-coding regions of a genome that contain satellite DNA - long stretches of DNA made up of repeating bases, or short tandem repeats (STRs) * as individuals likely have different numbers of repeats at a given satellite DNA locus, they will likely generate different DNA profiles

Answer 54

* DNA Sequencing (fluorescent nucleotides) * DNA Profiling (restriction enzymes) * Nanopore sequencing

Answer 55

* determines exact order of DNA bases * Used to confirm gene sequences, identify mutations, and study genetic variations

Answer 56

𝟭. Polymerase Chain Reaction * PCR machine used to amplify (make millions of copies of) a DNA sequence * Denatures DNA to single strands using high temperatures * Primers are annealed to DNA section that is to be amplified * uses a thermostable enzyme from thermophilic bacteria (Taq polymerase) to add bases to single strands 𝟮. Restriction Endonucleases/Enzymes * Restriction enzymes cleave DNA into fragments at specific recognition sites * REs "cut" DNA at STRs 𝟯. Gel electrophoresis * STR DNA samples are placed in small wells in a gel, and an electric current is applied * Negative charge at wells, positive charge at other end * DNA moves from neg to pos * smaller fragments (STRs) move faster than larger ones * Length of STR can be determined from where DNA fragments are in results

Answer 57

𝟭. Polymerase Chain Reaction * PCR machine used to amplify (make millions of copies of) a DNA sequence * Denatures DNA to single strands using high temperatures * Primers are annealed to DNA section that is to be amplified * uses a thermostable enzyme from thermophilic bacteria (Taq polymerase) to add bases to single strands 𝟮. Sequencing * Some nucleotide bases are fluorescently labelled as "stop" nucleotides * these nucleotides randomly stop the copying process at different points, creating DNA fragments of different lengths 𝟯. Gel electrophoresis * DNA samples are placed in small wells in a gel, and an electric current is applied * Negative charge at wells, positive charge at other end * DNA moves from neg to pos * smaller fragments move faster than larger ones * As the fragments spread through the gel, a full construction of the DNA segment appears as fluorescently labelled nucleotides * a laser detects the fluorescent labels and a computer assembles the sequence of bases based on the colour-coded base signals

Answer 58

* Nanopore = very small protein channel for DNA * An applied votlage causes ions to flow through the nanopores, which is detected as a small current * A computer detects the reduction in current as DNA passes through the nanopore * different bases cause different reductions * resulting signal is decoded by a computer to provide the specific DNA sequence

Answer 59

* Studying genetic diversity within and between populations can reveal high or low genetic differences * It has been proved that populations with high G.D. are more likely to survive changes better * This can be used in conservation management to increase G.D. of certain species to increase chance of survival * e.g. after floods, plants produced smaller seeds - Galapagos finches with smaller beaks survived while those with larger beaks died. If seeds became large, birds with small beaks would die and decrease whole population. Therefore, increased G.D. is important to conserve finch populations * Conservation genetics relies on gathering genetic data to make informed decisions * Allows kinship/relatedness to be determined so genetic diversity can be maintained * Identify individual who could be reintroduced into a population to ensure recovery * Any harmful alleles can be identified to ensure they are not passed on to future generations. * We can use the past to make accurate predictions about possible future extinction events e.g. Woolly mammoth.

Answer 60

* Population genetics is the study of the genetic composition of populations, including distributions and changes in genotype and phenotype frequency due to natural selection, genetic drift, mutation and gene flow * Observation of genetic phenotype and genotype frequency can give ideas about what alleles might be dominant * This can be used to see if disease causing alleles will show dominance or not * It can also be used to see if certain diseases can be inherited * It can be used to calculate probabilites of inheriting disorders/diseases

Answer 61

* Differences in genotype and phenotype frequency between populations can be used to infer the genetic relation between different races over time * Larger genetic distances between populations in sub-saharan Africa and those in Europe or Asia generated theory that people have migrated out of Africa and thus, the genetic variations in populations have split globally * However, another theory is that humans existed on all continents and genetic drift and gene flow are responsible for genetic differences between continents

Answer 62

* Enzymes that “cut” DNA in a sequence-specific manner * Serve as a natural defense mechanism for bacteria against viral infection * Can produce "blunt ends" or "sticky ends" * "Blunt ends" can join with matching "blunt ends" and "sticky ends" can join with matching "sticky ends"