Inheriting your physical traits

[Music] e [Music] d [Music] ch [Music] this young monkey looks a lot like his mother and this Colt looks like its mother young animals usually look like their parents but not in every [Music] detail children too usually resemble their parents but not exactly the physical characteristics or traits you inherited from your parents were transmitted from your mother through a tiny egg cell and from your father through a smaller sperm cell both was smaller than the tip of a [Music] needle when the sperm cell joined the egg cell they formed a fertilized egg the fertilized egg contained all the genetic information that eventually became you every person on Earth began this way from a tiny almost invisible Speck of living matter locked inside the fertilized egg with a tiny chromosomes containing the genetic material you inherited from your parents most of the chromosomes contributed by your mother could be matched with similar chromosomes contributed by your father 46 chromosomes that's all so small they can be seen only with a powerful microscope and they carry the genetic material that determined your physical traits the color of your eyes and skin the shape of your nose and mouth your face height weight six all of the physical traits that make you you are controlled by those 46 chromosomes a single pair determined your sex one chromosome from your father and one from your mother your mother contributed one of two sex chromosomes both of these chromosomes are of the type called X your father could contribute either an X chromosome or a smaller one of a type called y if he gave an X chromosome you became a female if he gave a y chromosome you became a male so the chromosome from the father determines the sex of The Offspring your 46 chromosomes determine not only your sex but most of your other physical traits since you receive half your chromosomes from your father and half from your mother why don't you look as much like one parent as the other why don't some people look more like their mother and some more like their father and why do some resemble neither parent but look like a grandparent the answer lies within the chromosomes in the chromosomes are the genes which control the inheritance of various physical traits most of the genes found in the chromosomes of your father can be matched with similar genes from the chromosomes of your mother scientists believe that many traits are determined by one pair of genes but more often by several pairs together when a trait is determined by just one pair often each gene is either dominant or recessive this means that one gene the dominant will hide or mask the effect of the recessive gene of a pair of genes causing eye color the gene for brown is dominant the gene for blue is recessive suppose one parent gave you a gene for blue eyes and the other one for brown eyes what color eyes would you have the dominant brown eye Jee would hide or mask the other and you'd have brown eyes can you have blue eyes if your parents have brown eyes yes if both of them had a dominant Brown Gene and a recessive blue Jee each parent would still have brown eyes in sexual reproduction they might each give you their recessive blue jean this pair of recessive blue jeans would give you blue eyes earlier we were wondering why sometimes we may look more like one parent than the other do you know a possible reason now because the genes you inherited from one parent affected your appearance more why do some people resemble neither parent their inheritance May reflect the characteristics of a grandparent or other ancestor some pairs of genes determining traits are not dominant and recessive instead some interact to produce a blend between two individuals for example when a zebra is M with a donkey The Offspring is a z broni a blend of its mother and father you may have a tall father and a short Mother and grow to be midway between their heights sometimes the genes for height interact to produce an individual whose height May range somewhere between the two parents so we've seen that genes can carry dominant traits recessive traits or as with this Offspring traits that produce a blend in recent years scientists have made remarkable progress in understanding chromosomes and genes they've learned a great deal about the molecular structure of DNA the main component of each gene yet there's still much to be learned about genes and chromosomes many questions remain unanswered is intelligence inherited can we increase it by knowing more about genes our artistic talents pass through the jeans or are they learned are musical talents inherited from musical parents or other ancestors can we learn the composition of genes well enough to one day prevent physical deformities scientists are only beginning to answer some of these questions all of the animals on the Earth pass on their physical traits from parents to offspring [Music] yet every Offspring is unique a little different from its parents and from all its other ancestors you too may look like your parents but you are also special no other person on Earth has your exact physical characterist I istics you began as a single Speck of matter containing thousands of genes and from these genes you inherited the physical traits you have [Music] today 46 chromosomes one unique human being generation after generation after [Music] Generation all of these people contributed to the final genetic combination that makes you you this is your gift from the past