Unit 8 Lesson 9: Organizing Data About Expressed Traits Flashcards
What are traits
Traits are individual characteristics of organisms, such as hair color, eye color, or blood type.
Wht are traits determined by
Traits are determined by genes which are found on sections of DNA.
What do genes carry
Genes carry codes that make proteins, and these proteins are responsible for the different traits that can be found.
How can the expression of traits be organized
The expression of traits can be organized by the frequency, distribution, and variation of the traits in a population.
What are alleles
Alleles are the different versions, or variants, of traits that are available for a gene.
Where do alleles come from
One allele will come from each parent.
When is the dominant allele expressed and what effect does its presnt have on the recessive allele
The dominant allele for the trait is expressed when it is present and will mask the recessive allele.
When will recessive alleles be present
The recessive allele will be seen when two recessive alleles are present for the gene.
What is genotype?
The combination of alleles found on the DNA is known as the genotype.
What does the genotype determine in an organism
The genotype, in turn, determines the phenotype of the organism.
What is the phenotype
The phenotype is the characteristic that can be observed, such as red flower color.
What is frequency
frequency – the number of times a particular trait is seen in a population
The cross of the red-flowered plant and the white-flowered plant yields offspring with a phenotype of
1 red:1 white. In other words, the frequency of red flowers is 50 percent, or 0.50. The frequency of white flowers is also 50 percent, or 0.50.
genetic drift
genetic drift – a change in the frequency of an allele in a population from generation to generation
what may cause genetic drift
a natural disaster or a smaller group of individuals moving away from the original population.
Where are the effects of genetic drift seen
This is a random sampling of the population, and the effects seem to be more evident in populations of smaller size.
Does genetic drift create new combinations of alleles
Genetic drift does not create new combinations of alleles
What does genetic drfit change
it just changes what alleles that the population contains are expressed.
Is genetic drift a source of genetic variation
This is not a source of genetic variation.
distribution
distribution – how the variation in traits is spread across a population
What does the distribusion show
The distribution shows how the variation in traits is spread across a population.
How can populations with normal distributions of traits be represented
Populations with normal distributions of traits can be represented in a bell curve
What is the meaning of polygenic traits
Polygenic traits are traits that are influenced by the genetic material in more than one gene.
What are some examples of Polygenic traits
Examples of polygenic traits include skin color, hair color, and height.
Can polygenic traits be predicted through Punnet Squaes
These traits are not as easy to predict through Punnett squares because they are often influenced by other environmental factors.
What does graphing the frequencies of the different presentations of traits show
Graphing the frequencies of the different presentations of traits will show that most organisms in the population are in the middle, with a few at each of the extremes at the ends
What is hair color influenced by
only about 2% of the world’s population have blonde hair. Hair color is also influenced by environmental factors which may cause variance in how these traits are expressed.
Founder effect
occurs when a small group of individuals establish a new population away from the original and can have a reduced diversity compared to the original
what impact does the founder effect have
The founder effect can impact the distribution of genetic diversity in a population.
When does founder effect occur
The founder effect is when a small sample of an original population leaves and establishes a new population.
How does founder effect impact the small population
The small population now has less genetic diversity than the original population because it is only a small sample from a much larger, diverse group.
inheritable genetic variation –
inheritable genetic variation – changes in genetic material that can be passed to offspring
What does genetic variation enable
Genetic variation enables natural selection and will increase the chances that some members of the population will survive.
natural selection
natural selection – the process in which organisms better adapted to their environment tend to survive and produce more offspring
Effect of natural selection
If there are any changes in the environment, the phenotype that is advantageous for the population will be the one that allows some organisms to adapt and survive.
Is genetic drift a source of genetic variation? Why or why not?
No, because there are no new combinations of alleles. Genetic drift is caused by either a random event that reduces the population or a smaller group leaving the original population. Both of these events will decrease the diversity of the gene pool but does not result in genetic variation.
Explain why graphing the distribution of traits in a population is important.
Graphing the distribution of traits can show where the majority of the organisms fall in the population. Any changes in the graph can indicate that there is an occurrence of natural selection taking place.
A population of meerkat is descendent from a few light gray tailed meerkats from a large population on the southern tip of Africa. Today, the new population has a high frequency of light gray tails whereas light gray tails were rare in the original larger population. Is the high frequency of gray tails in the new population a result of natural selection or founder effect? Support your answer.
This is known as the founder effect. The light gray tails were rare in the original population. A few individuals carried the rare trait and established the new population, where the trait was seen with a higher frequency
Where is genetic information located
Genetic information is located on DNA that make up chromosomes.
Where are chromosomes located
These chromosomes are located in the nucleus of cells and control the genetic makeup of organisms
What are genes
Genes are the codes for proteins that determine what traits are expressed.
The different versions of the genes that are available for traits are known as
alleles
What are examples of alleles
For example, there are alleles for eye color and hair color.
There are usually two different versions of alleles, what are they
dominant and recessive.
role dominant and recessive alleles
Dominant alleles mask or cover up other recessive traits. The recessive traits are seen only if two recessive alleles are present, and there are no dominant alleles for that gene.
What happens if there are two dominant alleles in gene pairs?
In this case, neither allele can mask the other, meaning that the alleles are codominant.
Codominance
neither allele is either completely dominant or completely recessive so both traits appear simultaneously
Examples of codominance include color in some flowers and coat colors in some cattle. Elaborate
For example, white cows have a dominant white allele while red cows have a dominant red allele. When a white bull mates with a red cow, both colors are seen in the coat of the offspring.
Examples of codominance
Examples include color in some flowers and coat colors in some cattle.
What is roan
When a white bull mates with a red cow, both colors are seen in the coat of the offspring. This red and white spotted appearance of the coat is called Roan.
There are some gene pairs where neither allele is dominant; what happens then
There are some gene pairs where neither allele is dominant, and when both alleles are present, both are expressed. The phenotype is typically somewhere between the two alleles. This is known as incomplete dominance.
Incomplete Dominance
a completely dominant allele is not present so a new version is expressed as a hybrid of the two
What are examples of incomplete dominance
Examples include some flower colors and curliness of human hair.
