genetics Flashcards
what are genes?
the basic physical and functional unit of hereditary
types of genes
monogenic and polygenic
what is an allele
a copy of a gene; maternal or paternal, an alternative form of a gene
what is the locus
the specific position of a gene on a chromosome
what are single nucleotide polymorphisms SNP
positions in a gene where more than one base may be present
what are mutations
random changes
homologous pair
similar chromosomes that have same locus and can work together
types of mutation
base substitution, insertion, deletion, inversion
what is that sickle cell anemia caused of?
sickle cell anemia occurs due to a base substitution mutation, a mutation in the gene that codes beta-globing polypeptide in hemoglobin. from GAG to GUG, which codes of valine instead of glutamine.
how many chromosome do humans contain?
46
what is a genome?
the whole of the genetic information of an organism
what was the aim of the human genome project?
their aim was to find the base sequence of the entire human genome
what did the human genome project lead to?
mapping
screening
ancestry
medicine
what are plasmids?
small, circular DNA that is capable of self replication
difference between prokaryotes and eukaryotes
prokaryotes: circular DNA no bound organelles naked DNA free DNA contain plasmids no mitochondria
eukaryotes: linear DNA organelles DNA packed with histones DNA in nucleus do not contagion plasmids have mitochondria
cell size
micrometer
centromere
a point the divides the chromosome into two
how many types of chromosomes do humans have?
23
when can chromosome visible?
during mitosis and misers, because they become much shorter and fatter due to supercoiling.
what are homologous chromosomes?
chromosomes that contain:
The same structural features (e.g. same size, same banding patterns, same centromere positions)
The same genes at the same loci positions (while the genes are the same, alleles may be different)
sexual reproduction
inherit genes from the mother and father, therefore, the organism will contain two copies of a chromosome( maternal and paternal), in which they are homologous chromosomes.
gametes:
sex cells, haploid cells n, 1 copy
diploid
two chromosomes, 2n
meiosis
results in haploid n, 23 chromosomes
mitosis
results in 2n, 46 chromosomes
heterosomes
sex chromosomes, X AND Y
autosomes
rest of the chromosomes from 1-22, do not determine the sex
females heterosomes
homologous XX
male heterosomes
XY
chromosome Y in males
initiates the development of male features, including testosterone. Y codes for TDF
karyograms
shows the chromosomes of an organism in homologous pairs of decreasing, therefore sex chromosomes are the shortest.
what is Down syndrome
a condition by which an individual has three copies of a chromosome instead of two
for example trisomy 21.
chromosome types
metacentric
submetacentric
acrocentric
Telocentric (not in humans)
difference between mitosis and meiosis
mitosis: diploid 1 division PMAT asexual cell reproduction groth and repair all cells genetically identical no crossing over, bivalents synapsis, or random assortment
meiosis: haploid 2 division gametes 2PMAT sexual cell reproduction crossing over, bivalents synapsis, or random assortment genetically distinct
meiosis
a reductional division to form haploid gametes, chromosome are replication once
homologous chromosomes
aligned in metaphase 1 separated in anaphase 1
sister chromatids
aligned in metaphase 2 separated in anaphase 2
in what phase is DNA replicated
interphase S phase (synthesis phase)
stages of meiosis
prophase 1 metaphase 1 anaphase 1 telophase 1 prophase 2 metaphase 2 anaphase 2 telophase 2
bivalents
a pair of homologous chromosomes are bivalents and process of pairing is synapsis.
crossing over
occurs only in p1 allows variation, the outcome of it is a junction is created where one chromatid in each of the homologous chromosomes breaks and rejoice with the other chromatid. crossing over occurs at a chiasmata.
random orientation
the alignment and pairing on homologous chromosomes in metaphase 1 is random,
possible combinations of random orientation
possible combinations is 2^n so for humans 2^23= 8million
non-disjunction
failure of separating at anaphase can lead to Down syndrome
what causes variation
crossing over
random assortment and orientation
random fusion of gametes
chronic villi sampling and amniocentesis
chronic is taking a sample from the placental tissue via a tube through the cervix, 1% risk of miscarriage
meanwhile amniocentesis involves the extraction of amniotic fluid with a needle (0.5%) risk of miscarriage.
mutations regarding chromosomes
somatic: single body cell cannot be inherited
gremline: sex chromosomes inherited
Mendel’s conclusions
Law of Segregation
Law of Independent Assortment
Principle of Dominance
homozygous
same alleles
heterozygous
different alleles
dominant
allele that is always expressed
cystic fibrosis
an autosomal recessive disorder caused by a mutation of a gene CFTR on chromosome 7
Huntington’s Disease
Huntington’s disease is an autosomal dominant disorder caused by a mutation to the Huntingtin (HTT) gene on chromosome
sex linked diseases
Haemophilia
Red-Green Colour Blindness
factors which can induce mutations
Radiation
Chemicals
Biological Agents
mutagens
agents the increase the rate of mutations
carcinogens
mutagens that lead to cancer
types of cancer
benign
malignant
pedigree charts
males=square
females=circle
PCR
an artificial method to replicate DNA in a laboratory
stages of PCR
Denaturation – DNA sample is heated to separate it into two single strands (~95ºC for 1 min)
Annealing – DNA primers attach to the 3’ ends of the target sequence (~55ºC for 1 min)
Elongation – A heat-tolerant DNA polymerase (Taq) binds to the primer and copies the strand (~72ºC for 2 min)
Gel electrophoresis
a laboratory technique used to separate and isolate proteins or DNA fragments based on mass / size
DNA profiling
a technique by which individuals can be identified and compared via their respective DNA profiles
transgenic
a new organism that is created by gene modification
risks of gmo
herbicide resistance release of toxins uncontrollable growth can be spread to non-targeted organisms cross pollination can lead to super weeds can limit biodiversity of an environment foods with gm are not labelled new traits can adverse health reactions removal of traits can have an unknown effect
clones
groups of genetically identical organisms derived from a single original parent cell.
Somatic cell nuclear transfer
a method by which cloned embryos can be produced using differentiated adult cells
natural cloning
species that reproduce asexually produce clones
Animal Cloning Methods
binary fission
budding
fragmentation
parthenogenesis
Plant Cloning Methods
spores
human cloning methods
Identical twins (monozygotic)
Non-identical twins (dizygotic)
Identical twins will be clones of one another (genetically identical), while non-identical twins will share 50% of the same
differentiated cells to generate cloned embryos can be used for two main purposes:
Reproductive cloning
Therapeutic cloning
GMO examples
BT crops golden rice flavr savr tomatoes glow in the dark animals aqua advantage salmon
recombinants
result due to crossing over as they are not identical to the parent cell
