genetic methods

Question 1

what is genetic research?

Answer 1

relatively new field of research (mid-19th century onwards)

considered to be study on heredity

Question 2

what is heredity?

Answer 2

the passing of mental and physical characteristics from one generation to another

Question 3

who was Gregory Mendel?

Answer 3

first geneticist

spent lot of time breeding and crossbreeding peas

noted peas get one version of each trait from each parent (allele)

some seen dominant (likely to be seen) while others are recessive

dominant traits are easily expressed in an organism’s phenotype

recessive traits only expressed in absence of overshadowing dominant trait

now know this is due to pea’s genotype - genes

Question 4

what is a genotype?

Answer 4

the underlying genetic makeup of a biological organism

aggregate of genes

Question 5

what is a phenotype?

Answer 5

the observable characteristics of a biological organism

physical or behavioural

Question 6

what is an allele?

Answer 6

version of a trait

many versions of that trait exist

one version of each trait from each parent

Question 7

what is a dominant allele?

Answer 7

allele that is expressed in the phenotype, even when there is only one copy present

capital letter

Question 8

what is a recessive allele?

Answer 8

allele that is only expressed when two copies are present in the genotype

lowercase letter

Question 9

what is Mendelian inheritance?

Answer 9

many of your phenotype traits will depend on your parents as your receive an allele of each gene from each

assuming both parents have a dominant and recessive allele, the proportion of dominant to recessive traits is 3:1

Question 10

what two fundamental laws does Mendelian inheritance rely on?

Answer 10

segregation - traits are either dominant or recessive

independence - varieties of each trait sort independently of each other

Question 11

what is DNA?

Answer 11

deoxyribonucleic acid

found in nucleus of every cell in an organism

genetic code of being

contains genetic instructions for the development, functioning, growth and reproduction of all known biological organisms

entire DNA of a being can be found in each individual cell

Question 12

what is DNA composed of?

Answer 12

two chains of nucleotides that coil around each other to form a double helix

adenine, guanine, cytosine, thymine (always matched A to T and C to G)

Question 13

what is translation?

Answer 13

strands are “unzipped” and read by ribonucleic acid (RNA) to produce protein strands

RNA used to read DNA

Question 14

what are chromatids?

Answer 14

when in cell’s nucleus, long strands of DNA called chromatids

usually tangled together when cell is active

when cell needs to divide (mitosis), chromatids undergo condensation - act of coiling tight like a spring to form a chromosome

Question 15

what are chromosomes?

Answer 15

typical humans have 46 chromosomes (23 pairs)

all pairs are XX aside from final pair which may vary

information on these chromosomes are biological programming behind life as we know it

Question 16

what is the final pair of chromosomes?

Answer 16

codes for biological sex

biological females = XX

biological males = XY

Question 17

what are genes?

Answer 17

individual sequences of DNA on chromosomes

Question 18

what does pleiotropic mean?

Answer 18

phenotype traits programmed by a single gene

Question 19

what does polygenic mean?

Answer 19

phenotype traits influenced by a combination of genes

Question 20

why study genes?

Answer 20

by understanding genes on a functional level, we’re able to open avenues of greater understanding of biology

by understanding base causes for many traits, can further target medicine, treatments and quality of life improvements

combating many genetic disorders

Question 21

why are some recessive traits more prevalently expressed in males compared to females?

Answer 21

because may not have a dominant allele of their (much shorter) Y chromosome

Question 22

what are x-linked conditions?

Answer 22

colour-blindness

Turner syndrome

Klinefelter syndrome

fragile X syndrome

triple X syndrome

Jacob’s syndrome

Question 23

what is colour-blindess?

Answer 23

first reported case of human X linkage

Question 24

what is Turner syndrome?

Answer 24

effects females

X partially missing

effects 1/2500

Question 25

what is Klinefelter's syndrome?

Answer 25

effects males XXY effects 1/720

Question 26

what is fragile X syndrome?

Answer 26

repeat on gene for FMR1 protein FMR1 necessary for typical brain development longer the repeat, more severe the symptoms 1/2 : 4000 males 1/6000 males

Question 27

what is triple X syndrome?

Answer 27

XXX individuals with three X chromosomes typically assigned female at birth most have no severe physical difficulties but may have slightly taller height and increased risk of mild developmental and learning challenges

Question 28

what is Jacob's syndrome?

Answer 28

XYY individuals have extra Y chromosomes typically assigned male at birth may be taller than average and have slightly higher chance of learning difficulties usually have normal sexual development and fertility

Question 29

what are sporadic mutations?

Answer 29

caused by errors or interference in typical cell division happen naturally or result of environmental factors (e.g. radiation) often include errors in chromosomal numbers

Question 30

what syndromes are caused by sporadic mutations?

Answer 30

Down's syndrome Williams syndrome

Question 31

what is Down's syndrome?

Answer 31

effects 1/1000 majority of cases due to trisomy (extra version of chromosome 21) some symptoms evident from birth while others may only become apparent later in life

Question 32

what is Williams syndrome?

Answer 32

effects 1/18000 due to microdeletion of chromosome 7 (approximately 25 genes) some symptoms evident from birth while others may only become apparent later in life

Question 33

what are polygenic traits?

Answer 33

conditions or disorders that rely on coding from multiple genes may not consistently follow Mendelian rules

Question 34

what is an example of polygenic disorder?

Answer 34

schizophrenia

Question 35

what is schizophrenia?

Answer 35

effects 20 million worldwide individuals are considered to be genetically predisposed to develop schizophrenia, suggesting clear genetic basis

Question 36

how can genetics be studied?

Answer 36

twin studies genomic studies targeted mutations

Question 37

what are twin studies?

Answer 37

compare monozygotic (genetically identical) and dizygotic twins

Question 38

what are genomic studies?

Answer 38

inspect genome of specific groups identify allele commonalties

Question 39

what are targeted mutations?

Answer 39

mutated lab produced genes inserted into chromosomes knockout genes knock-in genes

Question 40

what are knock out genes?

Answer 40

defective fail to produce a specific functional protein

Question 41

what are knock-in genes?

Answer 41

produce new or different proteins

Question 42

what is genetic engineering used for?

Answer 42

suggested to be on the verge of a genetic revolution technology such as CRISPR may allow us to directly edit our own genome currently being used to tackle big diseases such as HIV and cancer potential applications are huge may be an ethical nightmare