B1- You and Your Genes
Order of size ( smallest to largest):
gene, chromosomes, nucleus, cell
(REMEMBER GCNC- Give Cats Nice Cakes)
Chromosome = made of long molecules of DNA
Gene= section of DNA molecule
Fertilised Egg Cell contains GENES
Genes= Instructions for making proteins
Each Gene= instruction for making a different protein
Proteins= Structural AND Functional
Structural= build up body...collagen- protein found in tendons
Functional= take part in chemical reactions in the body....amylase-protein found in enzymes
GENES: CONTROL WHICH PROTEINS a cell makes = CONTROL WHAT a cell does and how an organism develops ....because they CONTROL which PROTEINS a CELL makes.
Environmental vs Genetic Factors
Twin Studies- Some things different when twins separated...PHYSICAL features same (how they look) BUT...WEIGHT different due to ENVIRONMENT= different
CLONING= helps scientists study effect of Environment on Growth and Development
Clone: Genetically Identical Organisms
Artificial Cloning= Take Cutting
Piece of adult plant cut off...Forms new roots/stems...Becomes small plant GENETICALLY IDENTICAL to ORIGINAL parent.
Clones= made from tint pieces of plants grown in AGAR jelly
Tall plant? partly down to genetics BUT what if not enough nutrients??? =WON'T GROW! Environmental Effects...Asexual Reproduction= Plant cutting cloning
Cause= Dominant Allele...75% Chance...Fatal Condition...Symptoms Appear At Mid Age...TWITCHING (hard to control muscles), STUMBLING, FORGETFUL,MOOD CHANGES, finally...cannot control movements
Genes Inherited??? How?
Passed on by parents...sex cells =half a set chromosomes from mother & father
Fertilised Egg Cell= FULL Set of Chromosomes (23 Pairs) because 2 sets one from Mother one from Father...Fertilised Egg Cell A.K.A Embryo
Body Cell= 23 Pairs of Chromosomes
Gender Chromosomes: XX-Female XY- Male Y=Sex Determining Gene...6 weeks Old= Male Testes develop caused by Y gene
Hormones- Chemicals that CONTROL many PROCESSES in CELLS
Testes= Produce male sex hormones called androgens= CAUSE embryo to develop into male
Genotype: Alleles You INHERIT... Think GENETICS!!!
Phenotype: What You LOOK Like... Think PHYSCIAL FEATURES!!!
Punnett Square: Genetic Diagram Predicting Genetic Features/Disorders Passed Down
Homozygous- the same...if both alleles same = HOMOZGOUS meaning you are HOMOZYGOUS for that CHARACTERISTIC
Heterozygous- different alleles...if both alleles different= HETEROZYGOUS meaning you are HETROZYGOUS for that CHARACTERISTIC
Cause= Recessive Allele...25% Chance...Problems for breathing/digestion...thick, heavy mucus builds up into lungs...blocks tubes...chest infection...lack of nutrients as Food isn't DIGESTED properly
Two Tests Checking If Embryo= Genetic Disorder
Amniocentesis vs Chorionic Villus TESTS....
AMNIOCENTESIS: Amniotic fluid withdrawn using syringe needle....1% miscarriage risk...not 100% reliable....very small risk of infection
CHRONIONIC VILLUS: Suction Tube removes cells from placenta...2% miscarriage risk....results at 10-12 weeks...almost no risk of infection...results not 100% reliable
ETHICS? Right VS Wrong
Terminating Pregnancy= Watching a Child suffer??...Unborn child- a right to life?..Personal/Religious beliefs?...
Deciding Right/Wrong Way to Behave = Ethical Question
Genetic Tests: Looking for alleles that CAUSE genetic disorders...Reliability??????
False Negative= Not DETECTING the Disorder False Positive= Detecting disorder when in fact NOT AT ALL present
Genetic Tests....also for wanting to know if carriers of a faulty allele
Genetic screening= Genetic testing whole population for a disease...COSTS/BENEFITS??...Everyone...Better to spend money on other things e.g. operations actually treating people with disorder
DNA testing kit- Tells…