Inheritance Flashcards
DNA
chemical that all of genetic material in a cell is made up of
name of a DNA molecule structure
double helix
gene
small section of DNA found in chromosomes
each gene codes for…
a particular sequence of amino acids which are put together to make a specific protein
how many amino acids are used and make up thousands of different proteins
20 amino acids
what do genes tell cells to do
tells cells in what order to put amino acids together
genome
the entire set of genetic material in a organism
why is understand the human genome very important
- allows scientists to identify genes in the genome that are linked to different types of diseases, which helps us develop treatment for it
- scientists can work out when new populations split off in a different direction and where they went
sexual reproduction
genetic information from two organisms (father and mother) is combined to produce offspring containing mixture of parents genes (why we inherit family features)
i’m sexual reproduction what do the mother and father produce
gametes by meiosis (egg and sperm cells in animals)
how many chromosomes does each gamete contain
23 (half number of chromosomes in a normal cell)
the mixture of genetic information that is created when two organisms sexually reproduce produces what
variation in the offspring
asexual reproduction
- only one parent
- no fusion of gametes
- no mixing of chromosomes
- no genetic variation (offspring are genetically identical)
asexual reproduction happens by…
mitosis, ordinary cell makes new cell by dividing in two
examples of asexual reproduction
- bacteria
- some plants
- some animals
differentiation
process by which a cell changes to become specialised for its job, carry out specific functions
used to repair and replace cells (skin or blood cells)
how many matched pairs of chromosomes are there that control your characteristics
22/23 pairs
what are the 23rd pair of chromosomes labelled and that do they do
- labelled XY or XX
- decide your sex, turn male or female
when making sperm what happens to the X and Y chromosomes
drawn apart in first division in meiosis
what is the percentage each sperm cell gets an X and Y chromosome
- X: 50%
- Y: 50%
what must both it’s alleles be if an organism wants to display a recessive characteristic
recessive (bb)
what must both it’s alleles be if an organism wants to display a dominant characteristic
BB or Bb
because the dominant allele (B) overrules the recessive allele (b)
genotype
combination of alleles you have
what is “b”
recessive, superpowers
what is “BB” or “Bb”
dominant, normal and boring behaviour
cystic fibrosis
- 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
cystic fibrosis allele
- recessive allele
- carried by about 1/25 people
can a person with one copy of the allele have cystic fibrosis
- no, they’re known as carriers
- both parents must be either carriers or have the disorder themselves for a child to have it (still 1/4 chance)
polydactyly
genetic disorder where a baby’s born with extra fingers or toes
polydactyly is caused by what
- a dominant allele
- can be inherited if just one parent carries it (50% chance of child getting it if other parent does not have it)
reasons to be against embryonic screening
- implies that people with genetic problems are “undesirable” could increase prejudice
- screening is expensive
- don’t want people to be too picky on what features their child will have
for embryonic screening
- help stop people suffering
- laws to stop it going too far, parents can’t select sec of their baby
variation
organisms of the same species look slightly different
examples of variation
- heights
- hair colour
- different shaped noses
most variation in phenotype is determined by a mixture of
- genetic factors
- environmental factors
mutation
- random change in organism’s DNA that can be inherited
- gene is altered, produced genetic variant (different form of the gene)
theory of evolution
all of today’s species have evolved from simple life forms that first started to develop over 3 billion years ago
natural selection
organisms with the most suitable characteristics for the environment would be more successful competitors and be more likely to survive
what happens to the organisms with suitable characteristic and survive
reproduce and pass on genes and characteristics to their offspring so then can repopulate
what happens to the organisms who are less well adapted with not so suitable characteristics to the environment
- less likely to survive and reproduce
- wont pass on genes to their offspring
- organisms with this characteristics will eventually be overpopulate and die out
what happens when over time phenotype organisms change so much
because of natural selection a new species is formed (speciation)
reason for why species go extinct
- environment changes too quickly (destruction of habitat)
- new predator kills them all (humans hunting)
- new disease wipes them out
- can’t compete against other species for food
- catastrophic event kills them (asteroid, volcano)
selective breeding
take the best plants or animals and breed them together to get the best possible offspring and repeat the process over generations to overpopulate and make all offspring have the same characteristics
reasons why some characteristics may be kept for selective breeding
- animals that produce more meat or milk
- crops with disease resistance
- dogs with a good, gentle temperament
- decorative plants with big flowers
gene pool
number of different alleles in a population
problems with selective breeding
- reduces gene pool, because farmers breed from the best (inbreeding)
- inbreeding can cause health problems because more chance of organisms inheriting harmful genetic defects when the gene pool is limited
- serious problem if a new disease appears, because there’s not much variation in the population
genetic engineering
to transfer a gene responsible for a desirable characteristic from one organism’s genome into another organism so it has the desired characteristic
process of genetic engineering (stage 1)
useful gene is isolated (cut) from one organisms genome using enzymes and is inserted into a vector
process of genetic engineering (stage 2)
vector usually a virus or a bacterial plasmid depending on the type of organism that the gene is being transferred to
process of genetic engineering (stage 3)
when vector is introduced to target organism the useful gene is inserted into its cell(s)
process of genetic engineering (stage 4)
this method can be used to do all sorts of things, like treat diseases
process of genetic engineering (stage 5)
transfer of gene is carried out when the organism receiving the gene is at an early stage of development (egg or embryo) this means that the organism develops with the characteristic coded by the gene
example of genetic engineering
- bacteria been genetically modified to produce human insulin that can be used to treat diabetes
- crops been genetically modified to improve size and quality of their fruit or make them resistant to diseases
cons of genetically modified crops
- reduce farmland biodiversity, affect number of flowers that live around the crops
- not fully safe, could have effects on human health
- transplanted gene may get into the environment (weed getting a herbicide resistance makes it a “superweed”)
pros of genetically modified crops
- characteristics chosen have increases food
- people living in developing nations lack nutrients, make a crop that could contain the nutrients needed
- already jerking grown without any effects or problems
fossils
- remains of organisms found in rocks from thousands of years ago
- provide evidence that organisms lived and how much or little they have evolved over time
examples of gradual replacement by minerals
- teeth
- shells
- bones
what are gradual replacement by minerals
- things that don’t decay easily and when buried can last a long time
- eventually replaced by minerals as they decay forming a rock-like substance
- surround sediment turns to rock but fossils stay distinct inside
casts and impressions (fossils)
things buried in a soft material like clay that hardens and preserves leaving an outline or impression (footprint pressed into soft clay material and hardens makes an impression)
preservation (fossils)
in amber there is no oxygen or moisture so decay microbes can’t survive instead they are just fully pressed in the clear yellow stone made from fossilised resin
why is this ur problem of antibiotic resistance getting worse
overused and inappropriate user of antibiotics
doctors prescribing them for non-serious conditions or infection d caused by viruses
why do it important to take all the antibiotics your doctor prescribes you
taking the full course makes sure that all the bacteria are destroyed and that there are none left to mutate and develop antibiotic-resistant strains
how is antibiotic used in animals
farmers give animals antibiotics to prevent them becoming i’ll which makes them grow faster
how is antibiotic used on animals in farming bad
used of antibiotics in animals can lead to development of antibiotics-resistant bacteria in the animals which can spread to humans via consumption (eating)
Linnaean system (made in the 1700s)
a system where living things are divided into kingdoms and then subdivided into smaller and smaller groups
what groups are made when the kingdoms of the Linnaean system are divided
- phylum
- class
- order
- family
- genus
- species
Three-domain system (made in 1990)
organisms divided into groups called domains then subdivided into small groups
what are the domains in the Three-domain system
- archaea
- bacteria
- eukaryota
archaea (three-domain system)
- organisms that are primitive bacteria
- often found in extreme places such as hot springs and salt lakes
bacteria (three-domain system)
- contains true bacteria
- look similar to archaea but have lots of biochemical differences
eukaryota (three-domain system)
includes a broad range of organisms including fungi plants, animals and protists
two part Latin name give em to every organism in the binomial system
- first part refers to the genesis of that organisms, gives information about the organism’s ancestry
- second part readers to their species
(humans = homosapiens)
why is the binomial system used worldwide
scientists in different countries who speak different languages all refer to the same name which avoids confusion
what do evolutionary trees show
- different species are all related
- common ancestors
- characteristics they’re likely to share
heterozygous
different alleles for a single characteristic (Bb)
homozygous
identical alleles for a characteristic (BB)
dominant
allele always expressed, even with just 1 copy of it
recessive
allele only expressed if 2 copies present (no dominant allele present)
phenotype
characteristic that is expressed (physical appearance like brown eyes)
conditions that increase the chance of fossils
- organisms dying in icy conditions
- organisms dying and falling into swampy waters
- organisms dying in acidic soils
conditions that reduce the chance of fossils
- weathering
- volcanic activity
- earthquakes
extinction
permanent loss of all members of a species
