Module 2.4 - Development, model organisms, frontiers of human genetics

Question 1

nanopore sequencing (ebola)

Answer 1

a DNA and RNA sequencing technology that utilizes nanoscale protein pores, called nanopores, embedded in a membrane to determine the sequence of nucleic acids

Question 2

pattern formation

Answer 2

the process by which patterns of gene expression are established, “the process by which spatial and temporal pattern of gene expression, which regulates cellular activities is organised within the embryo so that a well ordered structure develops”

Question 3

morphogenesis

Answer 3

the process by which form/shape of the embryo is established by cells, whose behaviour is determined by the genes they express

Question 4

asymmetric division

Answer 4

sister cells born different

Question 5

symmetric division

Answer 5

sister cells become different as a result of influences acting on them after birth

Question 6

cell-fate determinants

Answer 6

during an asymmetric division, internal molecules may be segregated to one cell after division which change the fate of those cells

Question 7

differentiation

Answer 7

the earliest cells in the embryo have the potential to give rise to many different cell types. As development proceeds, cells become increasingly specialised and restricted in their fates, due to expression of different genes. Eventually they achieve their final form and are terminally differentiated.

Question 8

morphogen

Answer 8

important mechanism for establishing different cell fates across a field of cells. Has a gradient of concentration, different concentrations result in different cell fates. e.g. bicoid in drosophila

Question 9

induction

Answer 9

cells produce a diffusable molecule which causes the cells it is in contact with to undergo a certain developmental fate (through a signalling pathway)

Question 10

egg-polarity genes

Answer 10

establish the overall anterior-posterior pattern of the embryo. Their expression pattern is established during formation of the egg. Bicoid is an egg-polarity gene which acts as a morphogen

Question 11

gap genes

Answer 11

have expression patterns that cover large regions of the embryo. Gap genes control the expression domains of other gap genes, e.g. Kruppel

Question 12

pair-rule genes

Answer 12

expressed in alternate stripes, e.g. even-skipped

Question 13

segment polarity genes

Answer 13

expressed in a subregion within each segment, e.g. Engrailed

Question 14

collinearity

Answer 14

order of expression along the anterior-posterior axis in the embryo is also the order in which the genes are found on the chromosomes

Question 15

homeotic selector (hox) genes

Answer 15

segment identity is determined by Hox genes. egg polarity, gap and pair rule genes combine to control the expression of Hox genes

Question 16

Sanger sequencing

Answer 16

uses bases that terminate polymerisation because they lack a 3’-OH (dideoxyribonucleoside triphosphate). Run a reaction for each base and each will produce a pool of DNA molecules that end at a particular base. You will then have all possible truncations of the DNA molecule. Run these on a gel and you can read the sequence based off of size (shortest at the bottom)

Question 17

Fluorescent dideoxt-NTPs

Answer 17

By labelling the 4 dideoxynucleotides with 4 different coloured fluorescent dyes and running them in a 1-D capillary, one can automatically read the fluorescence with a camera and computer. Roughly 800-1000 bp of sequence is possible per run. This was a key enabling technology for the human genome project.

Question 18

Next generation sequencing

Answer 18

Genome fragmented, sequence all the fragments at the same time, fragments then assembled into genome. Base with a block and dye is added, to a growing chain, photo taken of which base it is, then the block and dye is removed so the next base can get added on