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Science chapter 19
| Question | Answer |
|---|---|
| heredity | passing of traits from parents to offspring |
| trait | an inherited characteristics of an organism |
| allele | one of the different forms of a trait |
| chromosome | a rod or x shaped structure made of DNA |
| gene | a section of DNA that contains the information of one trait |
| genetics | study of heredity |
| dominant | A gene that determines a phenotype in combination with another gene it can mask other forms |
| recessive | a gene that is only expressed if there are no other dominant genes present, otherwise they are hidden or masked |
| homozygous | having two identical alleles for a trait (they are the same) |
| heterozygous | having one dominant and one recessive allele for a trait (they are different) |
| genotype | combination of genes for a trait |
| phenotype | way the genes are expressed, the way the organism appears for a trait |
| mitosis | nuclear division producing two identical cells with full number of chromosomes |
| meiosis | nuclear division producing four (non-identical gametes) with half the number of chromosomes |
| gamete | a sex cell (involved in sexual reproduction) |
| sperm | the male gamete |
| egg | the female gamete |
| somatic cell | a normal body cell, not a gamete |
| fertilization | the union (joining) of a male gamete and a female gamete |
| zygote | the cell resulting from fertilization |
| Punnett square | tool used to predict gene combinations and expressed traits of an offspring |
| Who was Gregor Mendel? | a monk in Australia, born in 1822 |
| What did Mendel study | garden peas, lifted the confusion on how traits are passed on from one generation to the next |
| An upper case letter represents what? | the dominant gene. for example he used "T" to describe the dominant Tallness gene |
| lower case letter is for what? | recessive gene |
| What happens with mitosis occurs in humans? | all 23 pairs of chromosomes duplicate and a full se of chromosomes passes into each daughter cell. |
| Why is mitosis important | because we need exact copies of cells to replace old or dying cells throughout our bodies |
| What happens in sexual reproduction | a new individual is formed that has different looks, abilities, and behavior from its parents |
| what happens in meiosis | parents produce sex cells (eggs or sperm) that contain exactly half as many chromosomes as body cells. |
| each male sex cell (sperm)has how many single chromosomes? | 23 single chromosomes |
| each female sex cell (egg) has how many single chromosomes | 23 single chromosomes |
| How many possible combinations can genes be paired | 4 |
| Who is Reginald Punnett | English Geneticist at Cambridge University |
| What did Reginald Punnett do? | developed a way to display the possible ways that genes could pair during genetic cross |
| What was the display called that Reginald Punnett developed? | "Punnett square" |
| What did the Punnett square look like | a large box divided into four small boxes |
| Where do you write the trait from the female parent in the Punnett square? | above the square |
| where did the same trait for the male parent go | left of the square |
| what did you write inside the squares | the possible outcomes |
| What does the Punnett square show? | the probability that specific genotypes will occur (it does not predict which gene will become the offspring's genotype) |
| Who is Dolly | a sheep that was cloned in march 1997 |
| How was Dolly created | from the DNA of just one parent |
| Dolly is from what species | a white sheep called Finn Dorset |
| How are identical twins formed? | from a single Zygote, they have identical genes |
| how are fraternal twins formed | from two different fertilized eggs. fraternal twins are not identical. they are like same ages sibling's. they do not have identical genes |
Created by:
mickeyfan1
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