bio topic 6

Question 1

DNA

Answer 1

• deoxyribonucleic acid- chemical that genetic material in a cell is made up of
• contains genetic material- instructions for an organisms

Question 2

gene

Answer 2

• codes for a specific protein
• geneis a small section of dna found on a chromosmes
• each gene codes a particular sequence of amino acids-make a specific protein

Question 3

alllele

Answer 3

different versions of one gene

Question 4

genome

Answer 4

• entire set of genetic material in an organism

Question 5

why is understanding whole human genome helpful

Answer 5

• allows scientists to identify genes in the genome that are linked to different types of diseases
• knowing which genes are linked to inherited diseases- treating them
• trace migration of certain populations of people around the world

Question 6

nucleotides

Answer 6

• made up of a sugar a phosphate group and one base
• bases apple turnover custard gravy- complementary base pairs
• each amino acid is coded for by a sequence of three bases

Question 7

mRNA

Answer 7

• proteins are made in the cell cytoplasm on tiny structures called ribosomes
• make proteins, ribosomes use the code in the dna- found in the cell nucleus and cant move cause too big
• mRNA is ade by copying code from DNA the mRNA acts as a messanger between DNA and the ribosome- carries code between dna and ribosome

Question 8

mutations

Answer 8

• random change in an organisms dna - sometimes inherited
• occur continuously can occur spontaneously
• change the sequence of the DNA bases in the gene which produces a genetic variant
• most dont have much effect on the protein
• some can change the protein

Question 9

mutations-insertions

Answer 9

• where a new base is inserted into the base sequence
• changes the way the three bases are read
• have a knock on effect

Question 10

mutations-deletions

Answer 10

• random base is deleted
• have a knock on effect

Question 11

mutations-substitions

Answer 11

• when a random base is changed to a different base

Question 12

sexual reproduction

Answer 12

• two organisms are combined to produce a genetically different offspring
• produces gametes
• ## in humans each gamete contains 23 chromosomes half the number of chromosomes in a normal cell

Question 13

asexual reproduction

Answer 13

• only one parent genetically identical to the parent
• happens by mitosis

Question 14

meiosis

Answer 14

• produce cells with half the normal number of chromosomes
• cell duplcates genetic information
• forming two armed chromosomes- one arm of each chromosome is an exact copy
• chromsomes arrange themselves into pairs
• first division– line up in centre of cell,pairs are pulled apart
• second division– chromosomes line up again in the centre of the cell arms of the chromsomes are pulled apart
• four gametes are produced

Question 15

Sexual Vs Asexual-EQ

Answer 15

• sexual- genetically different cells/ asexual- genetically identical cells
• sexual- involves meiosis/ asexual- involves mitosis
  -sexual involves fertilisation/ asexual- doesnt involve fertilisation
  sexual- more energy/ asexual- less energy

Question 16

organsims that reproduce by both sexual and asexual

Answer 16

• malarial parastites
• fungi
• plants

Question 17

what are charecteristics controlled by

Answer 17

• the genes you inherit control what charecteristic you develop
• all genes exist i different versions called alleles- two versions of every gene in your body
• two alleles for a particular gene are the same-homozygous
• ## two different alleles=heterozygous

Question 18

cystic fibrosis

Answer 18

• a genetic disorder of the cell membranes- results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas
• allele which causes cystic fibrosis is a recessive allele carried by 1 in 25
• because its recessive people with only one copy of the allele wont have the disorder they’re known as carriers

Question 19

polydactyly

Answer 19

• a genetic disorder where a baby is born with extra fingers or toes
• caused by a dominant allele and so can be inherited if just one parent carries the defective allele

Question 20

embryo screening- genetic disorders

Answer 20

• during in vitro fertilisation, embroyos are fertilised in a laboratory and then implanted into the mother’s womb
• before being implanted its possible to remove a cell from each embroyo and analyse its genes
• many genetic disorders can be detected this way

Question 21

for embryo genetic screening

Answer 21

• it will help to stop people suffering treating disorders
• costs the government a lot of money
• there are laws to stop it going to far

Question 22

against embryo screening

Answer 22

• implies that people with genetic problems are undesirable
• there may come a point where everyone wants to screen their embroyos so they can pick the most ‘desirable’ one
• screening is expensive

Question 23

mendel -pea plants

Answer 23

• gregor mendel noted how charecteristics in plants were passed on from one generation to the next
• results of his research were published in 1866 became the foundation of modern genetics

Question 24

mendel reached 3 conculsions

Answer 24

• charecteristics in plants are determined by hereditary units
• hereditary units are passed on to offspring unchanged from both parents
• hereditary units can be dominant or recessive

Question 25

Variation

Answer 25

differences in charecteristics caused by combination of inherited genes

Question 26

evolution

Answer 26

- theory of evolution: all of todays species have evolved from simple life forms that first started to develop over three billion years ago

Question 27

only the fittest survive

Answer 27

- organisms in a species show a wide range of variation in their charecteristics( phenotypic variation) - organisms have to compete for limited resources - organisms with the most suitable charecteristics for the environment would be more successful competitors and would be more likely to survive - successful organsims are more likely to reproduce and pass the genes for the charecteristics that made them successful to their offspring - over time beneficial charecteristics become more common

Question 28

speciation

Answer 28

development of new species

Question 29

extinction

Answer 29

when no species remain - environmental changes - new predator - new disease - cant compete - catastropic event

Question 30

not everyone agreed with darwin

Answer 30

- religous beliefs - wasnt enough evidence to convince scientists

Question 31

lamark

Answer 31

- changes that an organism acquires during its lifetime will be passed on to its offspring

Question 32

selective breeding

Answer 32

- select charecteristic you want - breed them - select the best offspring and breed them together - continue the process over several generations

Question 33

main drawback of selective breeding

Answer 33

- reducing gene pool- number of different alleles - imbreeding causes health problems

Question 34

genetic engineering

Answer 34

- useful gene is isolated from one organisms genome using enzymes and is inserted into a vector - the vector is usually a virus or a bacterial plasmid depending on the type of organsim that the gene is being transferred - when the vector is introduced to the target organism - `1

Question 35

classification ## Footnote Dear King Phillip, please come over for great spagetti.

Answer 35

*domain * kingdom * phyllus * class * order * family * genus * species

Question 36

speciation

Answer 36

1) populations of the same species 2) physical barrier separates the popu 3) different popu's start to adapt to their environments 4) overtime they become so different they are unable to reproduce

Question 37

explain how antibiotic resistance can arise

Answer 37

- random mutations occur within a bacterial population - Resistant bacteria are not killed / can survive in presence of antibiotic - Resistant strains survive AND reproduce - The alleles for resistance are passed on

Question 38

Bacteria can evolve rapidly explain why

Answer 38

- reproduce rapidly in optimium conditions

Question 39

why does antibiotic resistance give evidence for the theory of evolution

Answer 39

- Bacteria with resistance have alleles that allows them to survive in presence of antibiotic - Resistant bacteria have a higher chance of survival and chance to reproduce and pass their genes on - Resulting in a population of cells that are better suited to an environment containing antibiotic - Proving that offspring (daughter cells) inherit characteristics from their parent(s) (cells)

Question 41

mineralisation fossils

Answer 41

- gradual replacement by minerals, as teeth bones decay minerals replace them causing perfect model

Question 42

fossils-casts

Answer 42

organisms buried in soft material as material harderns organism decays

Question 43

fossils impressiosn

Answer 43

footprints

Question 44

fossils preservation

Answer 44

- no decay, organism stuck on amber or tar - organism stays intact