B1- You and Your Genes

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.

TWINS

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

HUNTINGTON'S DISEASE

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: **-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

CYSTIC FIBROSIS

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…