Mendel and the Gene Idea Flashcards
who is gregor mendel and what did he do?
gregor mendel discovered the basic principles of heredity through his work with garden peas.
by the 1800s, what was the favoured explanation of heredity?
the blending hypothesis: if you have a dark skin person and a light skin person having a kid, the baby will be medium skin tone.
did mendel agree or disagree with the blending hypothesis?
mendel disagreed with the blending hypothesis.
- he showed that discrete heritable units such as genes are passed on from parents to offspring. these genes maintain their distinct identities in offspring from generation to generation.
what did mendel study?
mendel studied 7 different characters of pea plants.
what is a character?
a character is visible feature of an organism. example: flower color, plant size
what is a trait?
a trait is variations of a character. example: purple flower, white flower, tall plant, short plant
what was the advantage of using the pea plant for his experiment?
- easy to grow
- grow to maturity in a single season
- many varieties
- easy to cross breed experimentally
what did mendel do in his experiment?
in his experiments, mendel crossed two contrasting, true breeding, varieties of pea plants. this meant he used one plant that always produces purple flowers: PP. and another plant that always produces white flowers: pp. he crossed these CONTRASTING TRUE BREEDING varieties of pea plants.
what does true breeding mean?
upon self pollination, an organism will produce offspring with the same traits. example: a true breeding purple flowered plant always produces offspring with purple flowers because the genetic makeup is PP: HOMOZYGOUS.
carpel vs stamen?
the carpel is the female reproductive organ: stigma, style, ovary
the stamen is the male reproductive organ: anther, filament
what does the fertilized ovule turn into? what does the mature ovary turn into?
the fertilized ovule turns into a seed.
the mature ovary turns into a fruit.
so what did mendel cross?
mendel crossed two true breeding parents.
purple flowered pea plant (female) x white flowered pea plant (male).
he CROSS POLLINATED THEM.
what is cross pollination?
cross pollination is when the pollen from the anthers of one flower is transferred to the stigma of another flower.
why is cross pollination important?
cross important is important because it increases genetic diversity which can improve resilience to diseases and environmental changes.
how exactly was cross pollination carried out?
- to prevent self pollination, the anthers of the receiving plant are cut.
- pollen is collected from the anthers of the white pea plant.
- the pollen is transferred to the stigma of the purple pea plant.
- fertilization occurs and ovules turn into seeds. the seeds contain a mix of genetic material from both the white and purple pea plants.
- the fertilized seeds are planted and when they grow into new plants, they are called the offspring: F1 generation. this is the step where the offsprings traits like flower color are observed.
what was the result of this (what color were the plants)
all offspring of F1 generation were purple. this is because the purple allele P is dominant over the white allele p.
is the white trait gone?
the white trait is not gone. it is still present in the F1 generations genetic makeup, it is just recessive and hidden by the dominant purple allele.
if the pollen from the purple flower was used instead, what would happen?
the same result: the flowers would be purple.
what is a reciprocal cross?
crosses made in both ways that end up with the same results are called reciprocal crosses
cross 1: use pollen from white flower and fertilize the purple flower.
cross 2: use pollen from the purple flower and fertilize the white flower.
in both cases f1 generation would still have the same result.
