key terms and concepts in genetics and genomics

Question 1

what is genetics?

Answer 1

study of genes and their inheritance

Question 2

what is genomics?

Answer 2

study of the genome

Question 3

what is the genome?

Answer 3

complete set of genetic material in a cell

Question 4

what are genes?

Answer 4

units of heredity, they are stretches of DNA that code for proteins and ran molecules that determine the characteristics of the host cell or organism

Question 5

what are chromosomes? where are they located?

Answer 5

long DNA molecules inherited during sexual or asexual reproduction in eukaryotes.
23 pairs in the nucleus
1 chromosome in the mitochondria

Question 6

what does the DNA go through to become a polypeptide protein?
are all DNA transcribed into coding RNA?

Answer 6

DNA is transcribed into a pre-mRNA (from promoter to terminator = introns and exons). then the pre-mRNA is processed so that the introns are spliced out and the pre-mRNA becomes an RNA. finally the mRNA is translated so that the mRNA becomes a polypeptide protein
however, many genes are transcribed into non-protein-coding RNA

Question 7

what are gametes? how many chromosome do they have? what do we qualify those cells as?

Answer 7

sperm and egg cells. they have 23 chromosomes. they are haploid cells

Question 8

what are somatic cells? how many chromosomes do they have? what do we qualify them as?

Answer 8

somatic cells are body cells that have 2 sets of 23 chromosomes (46 in total) and are qualified as diploid cells

Question 9

how many nucleotides are found in haploid cells? how many protein coding genes can be found?

Answer 9

3 billion nucleotides in haploid cells

20000 protein coding genes

Question 10

what is the proportion of nucleotides that form protein coding genes in diploid cells? what is the percentage if the introns are removed? what does the rest represent?

Answer 10

25%
2%
the rest represents introns, regulatory regions, non-protein-coding genes and repetitive and non repetitive DNA

Question 11

what is transcriptome? is it variable?

Answer 11

all RNA in a specific cell or type of cells

it is variable between cells

Question 12

what are exome? is it variable?

Answer 12

all exons in the genome

not variable

Question 13

what is the proteome?

Answer 13

complete set of protein expressed in a particular cell type at a particular time

Question 14

what is classical genetics?

Answer 14

looks at the visible results of a phenotype following sexual reproduction
we look at phenotypes to deduce genotypes

Question 15

what is sickle cell disease?

Answer 15

inherited blood disease where RBCs have a distorted sickle cell shape instead of the normal disc shape. these cells block blood flow through small blood vessels in limbs and organs which induces pain and organ damage

Question 16

what is a pedigree?

Answer 16

family tree that shows the phenotype of a certain gene

Question 17

what is forward genetics?

what is reverse genetics?

Answer 17

forward genetics: using phenotypes of futur generations to deduce the phenotype of older generations
manipulating the genotype and observing the impact on phenotype

Question 18

from what is formed haemoglobin? what changes when someone has SCD?

Answer 18

alpha2beta2 tetramer

when someone has SCD in the beta-glibin protein, glutamine is changed into valine which distorts the RBCs

Question 19

are heterozygous for the gene that causes SCD asymptomatic? if no what is this phenotype called?

Answer 19

no and small number of RBC have. sickle shape that can get higher with low O2
this phenotype is called sickle cell trait

Question 20

what is a monogenic disease? give an example

what are they referred to?

Answer 20

disease cause by a mutation in a SINGLE gene
SCD
they are referred to as Mendelian since they are inherited according to Mendelian rules

Question 21

what are the 5 types of monogenic diseases?

Answer 21

autosomal recessive –> may not occur in every generation
autosomal dominant –> every affected parent has an affected parent
x-linked recessive –> males are most often affected
x-linked dominant –> females are most often affected
mitochondrial –> passed on ONLY by females but can affect both sexes and appear in every generation

Question 22

what are polygenic/complex diseases?

Answer 22

depend on mutations in many genes

Question 23

can acquired disease caused by mutations in somatic cells (e.g. cancer) be passed on?

Answer 23

no

Question 24

can mutations in germ cells or early embryos be passed on?

Answer 24

yes

Question 25

how can the same genotype express different phenotype?

Answer 25

like identical twins this can be explained in terms of environmental and epigenetic influences on the phenotype

Question 26

what environmental agents can mutate our DNA?

Answer 26

chemical, physical or biological agents

Question 27

what is epigenetics?

Answer 27

mechanisms for altering the structural organisation of chromatin leading to changes in gene expression

Question 28

can molecular alteration alter the degree of DNA condensation and consequently gene expression without changing the nucleotide sequence?

Answer 28

yes. tags on histones

Question 29

what is the epigenome?

Answer 29

complete set of epigenetic tags on a particular genome at a particular time

Question 30

can epigenetic changes be maintained with cell division?

Answer 30

yes