BIOLOGY - DNA and inheritance - cell division and stem cells - variation and evolution Flashcards
what does allele mean
different form of the same gene
what does an asexual reproduction do
• produces genetically identical offspring from one parent only
• no fertilisation or gametes involved
what does base pairs mean
pair of chemicals
what does cancer mean
• disease caused by breakdown of the usual control mechanisms that regulate cell division (mitosis)
• Certain cells divide by mitosis uncontrollably and form tumours.
what does chromosome mean
coiled thread of DNA found in the nucleus of cells
what are clones in relation to reproduction or something
• offspring produced by asexual reproduction
• genetically identical to their parent organism
what does continuous variation mean
variations in which organisms do not belong to definite categories, but may fit in anywhere within a wide range, eg. height
what does cystic fibrosis mean
an inherited disease. its caused by a recessive allele of one gene - the CF gene
what does diploid mean
the number of chromosomes in a body cell
what does discontinuous variation mean
variation in which organisms belong to a distinct categories, eg. tongue rolling or blood groups
definition of DNA?
deoxyribonucleic acid - chemical molecule that genes are made of
what does dominant mean
the allele that shows in the phenotype whenever it is present
what does double helix mean
two parallel strands twisted together, a bit like a twister ladder
what does environmental variation mean
differences between organisms caused by the influence of the environment, eg, scars, tattoos, hair style
what does evolution mean
a sequence of gradual changes over millions of years in which a new species may be produced
what does f1 or f2 mean
short for first generation/second generation in a genetic cross
what does fertilization mean
the joining of male and female gametes to form a zygote
what does gamete mean
sex cell, eg, sperm and egg
what is a gene?
small part of a chromosome (or length of DNA) that controls a particular inherited characteristic.
each chromosome contains hundreds of genes.
what does gene therapy mean
• process of replacing disease carrying version of DNA in cells with the correct version
• so the cells can carry out all the processes to be healthy
what does genetic modification mean
a technique for changing the genetic information of a cell
whats genetic profiling mean
the artificial transfer of genes from one organism to another
what does genome mean
all the genetic information in an organism
what does genotype mean
the genetic makeup of an organism, eg, BB, or Bb. or bb
what does haploid mean
half the normal chromosome number/number of chromosomes in gametes
what does heritable variation mean
difference between organisms due to different genes, eg, eye colour
what does heterozygous/heterozygote mean
an organism that carries two different alleles for a particular characteristic, eg. Bb
what does homozygous/homozygote mean
an organism that carries two identical alleles for a particular characteristic eg, BB or bb
what does inheritance mean
the passing on of genes for characteristics and appearance from parents to offspring
what does meiosis mean
-type of cell division that is needed to make gametes ( sex cells) .
-Produces 4 haploid, genetically different daughter cells called gametes.
-Occurs in the ovaries and the testes only.
what does mitosis mean
-type of cell division needed for tissue growth, repair and replacement.
-produces 2 genetically identical daughter cells.
-Occurs in all tissues of the body
what does mutation mean
a change in the genetic material of an organism (new genes are created)
what does natural selection mean
the process which by species that have advantageous mutations that can help them survive will be able to live on and breed and pass those genes onto offspring
• a process where organisms that are better adapted to an environment, will survive and reproduce
• advantageous alleles of this variant organism are passed on to offspring
what does phenotype mean
a description of the outward appearance of an organism eg. brown eyes
what does recessive mean
the allele that is hidden when the dominant allele is present
what does selfing mean
fertilization of two gametes from the same organism, usually occurs in self fertilization in plants - pollen and ovule of same plant join at fertilization
what does sexual reproduction mean
the joining of male and female gametes, it results in genetic variation of the offspring
what does stem cells mean
unspecialized/undifferentiated cells that have the ability to divide and specialize into any other type of cell
what does variation mean
differences between individuals of the same species
what does zygote mean
a single fertilized egg
variation may be due to which 5 factors?
-genetics
-environment
-eye colour
-hair style
-intelligence
what are the two types of variation
continuous and discontinuous
how many chromosomes in a human cell
46 chromosomes
23 pairs
what is each chromosome made up of
a long coiled molecule called DNA
what is a short section of DNA called
a gene
a gene is made up of 4 bases
what are they/what do they stand for
and which do they pair with
G C A T
G - guanine
C - cytosine
A- adenine
T - thymine
G only pairs with C
A only pairs with T
because bases are different sizes and shapes, they called complimentary base pairs
the two chains with the ATGC bases in between them
= double helix DNA structure
the two chains are made out of what?
phosphate and sugar
what 3 things is DNA profiling used for
identification of relatives
Identification of criminals
identification of disease
(can also be used to identify different species for classification purposes)
what 3 steps are involved for genetic profiling
1) a sample of cells is collected from like saliva or hair or something.
2) DNA is “cut up” by enzymes so it ends up in fragments of different sizes
3) the fragments are separated using an electric current. A pattern of bands develops which is the “genetic profile”
- gain sample of cells from saliva/hair/something
- DNA “cut up” by enzymes, gain fragments of different sizes
- Fragments separated using an electric current. Pattern of bands develops <– the genetic profile
whats the male and female gamete
sperm for male, egg for female
what is mitosis needed for
tissue growth, repair and replacement
what is meiosis needed for
needed to make sex cells (gametes)
what are the two types of cell division
mitosis and meiosis
describe how mitosis works
produces 2 diploid, genetically identical daughter cells, and occurs in all tissues of the body. daughter cells have 46 chromosomes
• produces 2 diploids
• genetically identical daughter cells
• occurs in all tissues of the body
• daughter cells have 46 chromosomes
describe how meiosis works
produces 4 haploid, genetically different daughter cells called gametes, occurs in the ovaries and testes only. daughter cells have 23 chromosomes
• produces 4 haploids
• genetically different daughter cells called gametes
• occurs in ovaries and testes
• daughter cells have 23 chromosomes
compare sexual and asexual reproduction
asexual -
• 1 parent
• no fertilisation
• no gametes
• no variation in offspring
sexual -
• 2 parents
• fertilisation
• egg/sperm gametes
• variation in offspring
what happens when gametes join at fertilisation
they form a zygote , the zygote cell divides by mitosis, and a ball of cells called an embryo develops.
at this stage all the cells are unspecialised and are called STEM cells
• forms zygote
• zygote cells divide by mitosis
• ball of cells (embryo) develops
• this stage, cells are unspecialised and call STEM cells
what eventually happens to the unspecialised cells
they become specialised, eg become red blood cells, or muscle cells, etc.
where are stem cells found in adult humans
in the bone marrow, and can differentiate into new red/white blood cells
what are the ethical issues of using embryonic stem cells
the embryo is destroyed which is against some peoples moral beliefs
where are chromosomes found
in the nucleus
waht did people used to believe before we had an understanding of inheritance?
people used to believe in
the blending theory, eg, if a dad had black hair and the mother had blonde hair then the two colours would combine to make brown haired children
but then an austrian monk called gregor mendel disagreed with this theory and then did a few stuff and worked out how inheritance worked.
long story short, blending theory
what was the name of the Austrian monk who helped to shape our understanding of inheritance
and how did he do it
Gregor Mendel
-worked in a garden
-noticed that pea plants were either purple or white, not a combo of both
-crossed purple plants with white plants and only got purple offspring, he called the offspring F1 plants
- concluded that some inherited characteristics such as purple flowers had a stronger influence over the offspring. he called these stronger influences dominant and the weaker ones recessive.
-then he crossed two F1 plants together, for every 3 purple, there was 1 white flowering plant
-published work, rejected cuz DNA wasn’t known at the time, work was rediscovered later and people started to believe it
how do you try to prevent over exposure to U.V light
sunscreen
what are 3 symptoms of cystic fibrosis
-frequent chest infections
-severe coughs
-shortness of breath
what is genetic counselling
genetic counselling is when a genetic counsellor studies the family tree and predicts the probabilities of children being born with a genetic disease.
• when a genetic counsellor
• studies a family tree
• and predicts the probabilities of
• children being born with a
• genetic disease
why does gene therapy need to be repeated
cells eventually die and genes arent passed on if cells die
gene therapy is still being developed
suggest 3 issues revolving around the use of gene therapy for CF sufferers
-expensive
-dont know long term effects
-temporary
describe how gene therapy works
- a chromosome containing the healthy lung gene is removed from a cell
- the gene is cut out using enzymes.
- the healthy gene is packaged in a liposome (or harmless virus).
- this is cloned to make many copies
- the CF sufferer inhales these.
- the liposomes merge with the cells lining the airways.
- the normal, dominant gene is delivered into the lung cell
diagram in yo book, page 32, look at it ya fool.
genes control cell division (aka mitosis), if these genes get damaged, cells may divide too quickly, if this happens and uncontrolled mitosis occurs, a solid mass of cells form, what is this solid mass of cells called,
tumor
suggest 2 reasons how genes might get damaged (aka gene mutates i think)
- ionising radiation (like xray or Ultraviolet)
- carcinogen (tobacco)
3 ways how genes might get damaged (aka gene mutates i think)
- ionising radiation (like x-ray)
- chemicals (carcinogen) eg tobacco
- u.v light
list 3 species that are now extinct
and what evidence do we have that they once existed?
dodo (dodo is a bird thingy if you didnt know)
dinosaur
mammoth
evidence = fossils
In the 19th century two people put out an explanation on how organisms evolved, they called it natural selection
who are they and what was their explanation
Darwin and wallace
explanation;
1. all organisms over reproduce, have more offsprings than can survive, so more competition for resources, mutations can occur which gives variation within population
- some variations, eg being able to run faster to escape predators may give survival advantage
- best adapted organisms are more likely to survive, and live longer and breed, - “survival of the fittest to bread”
- the survivors pass on their advantageous genes to their offspring and this is called natural selection.
wat did wallace and darwin say about species being extinct or evolving
species change/evolve over time in response to the changing environment.
species that fail to evolve become extinct
what is genome mapping
• something to do with editing a gene
illegal in most cases since people will make “designer babies” edit their own children to be what they want
Eventaully all children will look teh same or something
and lead to an un-reproducable society
genetic modification can be used to make human insulin, explain the process
• extract insulin gene from human pancreas cell
• cut plasmid DNA
• insert gene in plasmid
• put plasmid back into bacterium
• bacterium multiplies in fermentation tank
• produces human insulin
• human insulin extracted
• then purified and bottled
————————————————————–
• can be made in large quantities
• and is cheaper and quicker than before
• also fewer side effects
(how are u learning this man ): )
Hiya
B(
No
Yes
what are 3 advantages and disadvantages
of
growing soya bean crops that have been genetically modified for herbicide resistance
advantages
-can spray soyabean crops with herbicide without harming them.
-greater crop yield (so cheaper food and able to supply global demand)
-less herbicide is used so environment freindly
disadvantages
-could harm wild life, reducing biodiversity
-people worry about health if they eat genetically modified crop, dont know long term effects (unknown long term effects)
-genes can pass on to weeds creating “super weeds” that cant be killed by herbicide.
