story of us 3.14, 3.15, 3.16B, 3.17B, 3.33, 3.22, 3.19, 3.20, 3.23, 3.24, 3.25, 3.21B, 3.26, 3.27

Question 1

what does dna stand for?

Answer 1

deoxyribonucleic acid

Question 2

what does dna do?

Answer 2

stores the genetic information and controls cell activities
- contains instructions for building all proteins within an organism
- in eukaryotes it is found within the nucleus as linear (straight) chromosomes
- in prokaryotes it is the cytoplasm in the form of a circular chromosome and many small plasmids

Question 3

what shape is dna?

Answer 3

a double helix shape

Question 4

what is dna made up of?

Answer 4

nucleotides
- they consist of sugar (deoxyribose), a phosphate and nitrogenous base

Question 5

what are the four types of nitrogenous bases?

Answer 5

• adenine A
• cytosine C
• guanine G
• thymine T

Question 6

how are the nucleotides joined together?

Answer 6

joined by covalent bonds between the sugar of one nucleotide and the phosphate group of the next nucleotide- forming the sugar phosphate backbone

Question 7

what is adenine always paired to?

Answer 7

thymine

Question 8

what is cytosine always paired to?

Answer 8

guanine

Question 9

what does rna stand from?

Answer 9

ribonucleic acid

Question 10

what shape is rna?

Answer 10

joined to form a single strand

Question 11

how are nucleotides joined in rna?

Answer 11

joined by covalent bonds between the sugar of one nucleotide and the phosphate of the next

Question 12

how is rna and dna different?

Answer 12

• rna is single stranded and dna is double stranded
• rna has a sugar called ribose and dna has a sugar called deoxyribose
• rna has a base uracil U and dna has the base thymine T

Question 13

what are the two types of rna?

Answer 13

messenger rna - mRNA
transfer rna - tRNA

Question 14

what is the messenger rna?

Answer 14

formed in the nucleus of the cell, copies the sequences of bases of a section of dna this is called TRANSCRIPTION

Question 15

what is the transfer rna?

Answer 15

found in the cytoplasm, tRNA picks up specific amino acids from the cytoplasm and brings them into the position on the surface of the ribosome where they are joined together to make a specific protein called TRANSLATION

Question 16

what is a gene?

Answer 16

a gene is a length of dna which codes for a protein
- provides information on sequence of amino acids in a protein
- proteins control chemical reactions, growth, colouration, and all inheritable characteristics
the code is universal

Question 17

what do you call the every three bases?

Answer 17

codon

Question 18

what is dna wrapped in?

Answer 18

wrapped in structure called chromosomes
- each person has two chromosomes (one from mother, one from father)

Question 19

what did special about genes controlling a specific characteristic?

Answer 19

situated at the same point on each chromosome so we say the chromosomes are homologous
- pair of genes for each characteristic in every diploid nucleus

Question 20

what are alleles?

Answer 20

genes that have different versions, which code for different forms of a protein

for example, the gene for eye colour has alleles coding for proteins which appear brown, green or blue

Question 21

what is a genome?

Answer 21

is one copy of all an organism’s dna, in humans this is all the dna that makes up the 23 pairs of chromosomes found in all diploid body cells
EXCEPT sex cells or gametes, which is only half of a persons genome (haploid)

Question 22

how many chromosomes in humans?

Answer 22

contains two copies of each of their 23 chromosomes, a diploid cell

Question 23

what is the 23rd chromosome?

Answer 23

the sex chromosome, which determines your sex
XX - female
XY - male

Question 24

what is sex is XX?

Answer 24

female

Question 25

what sex is XY?

Answer 25

male

Question 26

what are human gametes?

Answer 26

haploid so when they fuse they form a diploid offspring

Question 27

what is mitosis?

Answer 27

producing genetically identical daughter cells
these cells are diploid
used for growth, repair, asexual reproduction

Question 28

what is meiosis?

Answer 28

produces haploid gametes (sperm, eggs) which are not genetically identical
meiosis is only used to produce gametes for sexual reproduction

Question 29

what is variation in?

Answer 29

particular characteristics like eye colour, it can be genetic, environmental or a combination of both

Question 30

variation:
genetic

Answer 30

following sexual reproduction or mutation, organisms will have different versions of genes to another individual

pea plant might have the alleles or a height gene to be tall or a dwarf

Question 31

variation:
environmental

Answer 31

the environment might also affect the characteristics of an organism

pea plant might gain more sunlight and able to photosynthesise more than a pea plant in the shade

Question 32

what are the two types of variation?

Answer 32

continuous
discontinuous

Question 33

what is continuous variation?

Answer 33

example - height where there is a smooth range of measurements

more heavily influenced by environmental factors

Question 34

what is discontinuous variation?

Answer 34

example, blood group where there are distinct categories with no values in between

Question 35

what is homozygous?

Answer 35

both parents have the same allele ( tt and TT)

Question 36

what is a dominant allele?

Answer 36

needs only one allele present to be expressed

Question 37

what is a recessive allele?

Answer 37

needs two alleles to be present to be expressed

Question 38

what is heterozygous?

Answer 38

both contain one of each allele (Tt)

Question 39

what is the genotype?

Answer 39

combination of alleles

Question 40

what is the phenotype?

Answer 40

what is expressed

Question 41

what does the upper and lowercase letters represent in a genetic cross?

Answer 41

upper case - dominant
lower case - recessive

Question 42

what is cystic fibrosis ?

Answer 42

a disease which effects the lungs, affects the CFTR proteins which causes mucus to be incredibly thick so thick that he can’t be removed from lungs
can reduce life expectancy to 30 years, no cure

Question 43

what is codominance?

Answer 43

some alleles don’t show a perfect dominant and recessive relationship
therefore there are actually three phenotypes possible even though there are only two alleles

Question 44

what is a pedigree diagram?

Answer 44

family trees used to determine the probability of inheriting a genetic disease

Question 45

what is the likely hood of having a boy or a girl?

Answer 45

50:50

Question 46

what is an allele?

Answer 46

a version of a gene