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Biology Leaving Cert > RNA and DNA, Genetic Crosses > Flashcards

RNA and DNA, Genetic Crosses Flashcards

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1
Q

DNA and RNA creator and overview

A

Watson and Crick
nucleic acids
either dna or rna are present in viruses, never both

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2
Q

chemical composition of chromosomes

A

DNA and protein

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3
Q

dna structure

A

double helix
each strand is composed of nucleotides: deoxyribose sugar, phosphate, nitrogeneous base
complementary bases from opposite strands held together by hydrogen bonds

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4
Q

nitrogenous bases

A

adenine- thymine

cytosine- guanine

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5
Q

dna vs rna

A

dna - double stranded
rna- single stranded

dna- sugar is deoxyribose
rna - sugar is ribose

dna - bases A,T,C,G
rna - bases A,U,C,G

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6
Q

dna location

A

nucleous

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7
Q

rna location

A

cytoplasm , ribosome

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8
Q

genotype

A

genetic make up eg bb,Bb,BB

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9
Q

phenotype

A

physical make up eg brown eyes

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10
Q

dominant

A

where one allele masks the effect of another allele

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11
Q

recessive

A

where an alleles effect is only expresses when in the homozygous condition

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12
Q

homozygous

A

two alleles for a trait are the same eg BB

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13
Q

heterozygous

A

two alleles for a trait are different eg Bb

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14
Q

incomplete dominance

A

neither allele masks the effect of the other- both alleles are equally expressed in the heterozygous genotype to produce an intermediate phenotype

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15
Q

sex linked

A

when a gene is located on a sex chromosome

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16
Q

pedigree study

A

a diagram showing the genetic history of a group of related organisms

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17
Q

linkage

A

genes for different traits located on the same chromosome

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18
Q

locus

A

the position of a gene on a chromosome

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19
Q

non nuclear DNA

A

DNA that is not located in the nucleus ( found in mitochondria)

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20
Q

segregation

A

separation of alleles

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21
Q

monohybrid crosses

A 
write a key
order of cross:
parents phenotype
parents genotype
meiosis and gamete formation
fertilisation (punnet square)
offspring genotypes
offspring phenotypes
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22
Q

incomplete dominance crosses

A

same steps as monohybrid

23
Q

sex linked crosses

A

write a key
write down sex chromosomes for each parent, assign thr correct allele to each chromosome, none to Y
same steps as monohybrid

24
Q

where does a son get his x and y

A

y from father
x from mother
if he has a sex linked condition, it must come from the mother as Y doesnt carry many alleles

25
Q

non-nuclear inheritance

A

inherited from the mother
can lead to inheritance of muscular disorders such as lack of ATP production
why: during fertilisation, the acrosome of the sperm cell enters the egg to fuse with the nucleus, but the midpiece which contains the mitochondria doesnt enter the egg

in plants: chloroplasts inherited from mother

26
Q

when both parents are heterozygous for both traits (dihybrid cross)

A

9:3:3:1

27
Q

dihybrid crosses

A

inheritance of two traits
four letters for each parent eg BbHh
same steps as hybrid cross

28
Q

significance of two allele pairs on different chromosome pairs (not linked)

A

gives rise to more variation in offspring ( independent assortment)

29
Q

linkage

A

genes for different traits are located on the same chromosome
gives rise to less variation as a result of fewer possible gene combinations

30
Q

Gregor Mendel

A

father of genetics

studied traits in peas

31
Q

first experiment mendel

A

pure bred tall x pure bred small

results: ratio 3:1 tall : small

32
Q

law of segregation

A

organisms contain two alleles for every trait

these alleles separate at gamete formation, each of which containing one copy of each allele

33
Q

second experiment mendel

A

pure bred tall and purple x pure bred small and white

results: all offspring tall and purple

34
Q

law of independent assortment

A

either member of a pair of alleles can pass into a gamete with either member of another pair of alleles

more variation occurs as a result

35
Q

exceptions to mendels laws

A

linked genes : are inherited together, give rise to less variation
sex linked genes: where alleles are located on a sex chromosome

36
Q

purine bases

A

adenine

guanine

37
Q

pyramidine bases

A

cytosine

thymine

38
Q

DNA replication

A

production of an identical copy of DNA in a cell
during interphase
1. DNA helix unwinds, hydrogen bonds are broken by enzymes and strands separate
2. complementary base pairs on free nucleotides attach to exposed bases - joined together by DNA polymerase
3. Each DNA molecule winds back into a helix shape

39
Q

significance of DNA replication

A

all cells produced as a result of cell division have identical genetic information to each other

40
Q

DNA profiling

A

making and examining a pattern of bands from the DNA of one person which can be compared with the DNA profile of another person

41
Q

describe DNA profiling

A
  1. DNA extraction: cells broken down to release DNA
  2. DNA cut into fragments using restriction enzymes
  3. Fragments separated by gel electrophoresis based on size (smaller fragments move farther)
    DNA (negatively charged) moves toward +ive terminal
  4. Pattern of fragments compared
42
Q

applications of dna profiling

A

medicine: look for genetic matches in organ transplants
forensic science: comparing victim and suspect blood samples
relationships: maternity/paternity disputes

43
Q

genetic screening

A

testing for the presence of a specific or altered gene
applications:
adult - identifying carriers of a defective gene eg cystic fibrosis, haemochromatosis - deciding whether or not to have a family
embryonic- predictive testing for a genetic disorder

44
Q

RNA types

A

mRNA
tRNA
rRNA

45
Q

messenger rna

A

located in nucleus
composed of codons complementary to dna strand
three types of codons/ nature of the genetic code:
1. start codon
2. amino acid codon
3. end codon
function: carries info (code) for a specific protein from the nucleus to a ribosome

46
Q

ribosomal rna

A

located in the ribosome in the cytoplasm
function : structural component of a ribosome by combining two ribosome subunits together
forms weak bonds with mRNA and attaches tRNA to mRNA

47
Q

transfer rna

A

located at the ribosome attached to mRNA
function: transports amino acids to the mRNA and attaches to mRNA

How :
carries anticodons
carries amino acids at the other end and aligns in the correct sequence

48
Q

transcription

A

copying a sequence for bases from DNA to mRNA with the aid of RNA polymerase in the nucleus of a cell

49
Q

outline transcription

A

DNA unwinds at specific base sequence
RNA nucleotides from cytoplasm match with their complementary DNA bases in the nucleus
RNA polymerase binds the nucleotides together = mRNA
mRNA leaves nucleus

50
Q

RNA polymerase

A

anabolic enzyme

51
Q

structure of a protein

A

long chain of 20 amino acids

amino acid sequence determines structure and function of the protein

52
Q

translation

A

synthesis of proteins by forming chains of amino acids in the ribosome with the help of mRNA , rRNA and tRNA

53
Q

outline translation

A

mRNA forms weak bonds with rRNA and ribosome
mRNA contains start codon, amino acid codon, stop codon
tRNA matches its anticodons with complementary codons on mRNA, each tRNA also carries a specific amino acid to the anticodon
tRNA continues to carry amino acids to the mRNA until a stop codon is reached

54
Q

last step in protein synthesis

A

proteins fold to carry out its function efficiently, allowing it to reach its 3D shape

Biology Leaving Cert (34 decks)

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