Science – Genetics: The Study of Heredity – Flashcards

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Heredity
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The passing on of physical characteristics from parents to offspring (traits from one generation to the next)
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Gregor Mendel
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Considered the father of genetics because of his work with cross-pollinating pea plants
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Trait
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A specific characteristic that an organism can pass on to its offspring through its genes
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Genetics
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The scientific study of heredity (what is passed down from generation to generation by DNA)
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Fertilization
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Occurs when the sperm from the male connects with the egg of the female and a new organism begins to form
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Purebred
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An organism that is the offspring of many generations that have the same traits.
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F1 Offspring
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The "First Filial Generation" - The sons and daughters of two purebred plants that have been cross-pollinated. Mendel crossed purebred tall plants with purebred short plant, but the results was ONLY SHORT plants.
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Filial
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Son or daughter of the F1 generation
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F2 offspring
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The "Second Filial Generation" - Sons and daughters of cross-pollinated plants that showed traits from the original parents. Mendel allowed the fully-grown F1 plants to self-pollinate - surprisingly, the Second Filial generation were a mix of BOTH tall (3/4 th's, or 75%) and short (1/4 th, or 25%) plants. The SHORT trait had reappeared.
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Genes (definition 1)
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Factors that control a trait (that are passed on from one generation to the next)
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Alleles
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Different forms of a gene. Dominant traits will ALWAYS show up in offspring, and recessive traits will ONLY show up WHEN PAIRED WITH ANOTHER RECESSIVE TRAIT.
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Dominant Allele
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The trait that ALWAYS shows-up in the (new/offspring) organism when the dominant allele is present (like the TALL trait in Mendel's experiments)
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Recessive Allele
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A trait that is hidden whenever the dominant allele is present. This trait will ONLY show-up IF the organism does NOT have the dominant allele.
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Hybrid
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An organism that has 2 different alleles for a trait - it is HETEROZYGOUS for a particular trait.
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Probability
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- A number that describes how likely it is that an event will occur. - The laws of probability predict what is LIKELY to occur, NOT necessarily what WILL occur. - Mendel realized that the mathematical principles of probability could be used to predict the results of genetic crosses.
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Punnett Square
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- A chart that shows all the possible combinations of alleles that can result from a genetic cross. - A visual representation of the events that occur at MEIOSIS.
question
Using a Punnett Square, you can...
answer
see the different combinations of genetic crosses that will result in the offspring as a result of traits that are passed on from the parents. Each parent contributes one allele to each offspring.
question
Phenotypes
answer
Physical appearance and visible traits in an organism
question
Genotypes
answer
An organism's genetic make-up, or allele combinations
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Homozygous traits
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An organism with that has 2 IDENTICAL alleles for a trait.
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Heterozygous traits
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- An organism with that has 2 DIFFERENT alleles for a trait. - Also known as "HYBRID"
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Codominance
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Occurs when the alleles are NEITHER recessive or dominant, but both traits (alleles) show up in the offspring
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Walter Sutton and his "hypothesis"
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- American geneticist who wanted to understand how sex cells form. - He studied grasshoppers and "hypothesized" (thought) that chromosomes were the key to understanding how offspring have the traits of their parents.
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Sutton's Observations and Discovery
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- That a grasshopper had 24 chromosomes, and its offspring ALSO had exactly 24 chromosomes. - The chromosomes existed in 12 pairs, with ONE chromosome in each pair from the MALE parent and ONE chromosome from the FEMALE parent.
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Body/Sex cells in grasshoppers
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Body cells of a grasshopper have 24 chromosomes, while sex cells only have 12. Also, the 24 chromosomes existed in 12 pairs.
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Chromosome theory of inheritance
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- Genes are carried from parents to their offspring ON chromosomes - Alleles are literally carried ON the chromosomes of the parents and passed to the offspring.
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Meiosis
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The process by which the number of chromosomes is reduced by half to form sex cells (sperm and eggs)
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Sex cells
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Sperm and Eggs
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During Meiosis...
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- The chromosome pairs separate and are distributed to TWO different cells. - The resulting sex cells have only HALF as many chromosomes as the other cells in the organism
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Chromosome Pairs
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- Each sex cell has ONE chromosome from each original pair. - However, the offspring still ends-up with the normal number of chromosomes because it receives half from each parent. - HUMANS HAVE 23 PAIRS OF CHROMOSOMES (vs. grasshoppers who have 24 pairs)
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Genes on Chromosomes
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- Chromosomes are made up of many genes joined together like beads on a string. - The chromosomes in a pair may have DIFFERENT alleles for some genes, and the SAME alleles for others.
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20,000-25,000
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The number of chromosomes you have in your body, even though you only have 23 pairs
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The Main Function of Genes
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- To control the production of proteins in an organism's cells - To contain the code that determines the structure of a protein.
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Chromosomes and DNA
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- Chromosomes are composed mostly of DNA. - A gene is a section of a DNA molecule that contains the information to code for ONE specific protein.
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Proteins
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Help to determine the size, shape, color, and many other traits of the organism
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DNA and Nitrogen Bases
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DNA of made up of FOUR Nitrogen Bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). These bases form the "rungs" on the DNA ladder
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Nitrogen pairs
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AT and CG
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Gene (Definition 2)
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A section os a DNA molecule that contains information to code for a specific protein
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How Many Bases a Gene May Contain
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A single gene on a chromosome may contain several hundred to a million or more nitrogen bases
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The Order of Nitrogen Bases
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Forms a genetic code that specifies what type of proteins will be produced
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Chain Molecules
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Proteins made of individual amino acids
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Protein Synthesis
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- During this process, the cell uses information from a gene on a chromosome to produce a specific protein. - Takes place on the ribosomes in the cytoplasm of the cell
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During Protein Synthesis...
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The cells use information from a gene on a chromosome to produce specific proteins
question
Before Protein Synthesis can take place...
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- A 'messenger' must first carry the genetic code from the DNA (located inside the nucleus) to the cytoplasm (located outside the nucleus). ****- This genetic "messenger" is called "RNA" (Ribonucleic acid) - ****
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Messenger RNA
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Copies the coded message from the DNA in the nucleus, and carries the message to the ribosomes in the cytoplasm.
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Transfer RNA
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Carries amino acids to the ribosomse and adds them to the growing proteins.
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How many "strands" does DNA, and RNA, have?
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DNA has 2 strands RNA only has one strand
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How is RNA formed?
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- RNA bases pair-up with DNA bases: - Guanine always pairs with Cytosine; and Adenine always pairs with Uracil. - So, RNA contains: Guanine, Cytosine, Adenine, and Uracil.
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What id the difference between the DNA and RNA combination of "bases?"
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Uracil takes the place of Thymine in RNA (DNA contains: RNA contains: Guanine, Cytosine, Adenine, and Thymine. RNA contains: RNA contains: Guanine, Cytosine, Adenine, and Uracil.)
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Protein Synthesis, Step One
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DNA provides code to form messenger RNA
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Protein Synthesis, Step Two
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Messenger RNA attaches to Ribosome
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Protein Synthesis, Step Three
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Transfer RNA attaches to Messenger RNA
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Protein Synthesis, Step Four
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Protein Production Continues
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Mutations
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Can cause a cell to produce an incorrect protein during protein synthesis. The organism's trait, or phenotype, may be different from what it normally would have been.
question
Mutation in Body Cell
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The mutation will not be passed on to the offspring
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Mutation in a Sex Cell
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The mutation can be passed on the offspring
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Where Mutations occur
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DNA replication process
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Chromosomes incorrectly separating during Meiosis
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When this mutation occurs, a cell can end up with too many or too few chromosomes
question
A Mutation is harmful if...
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It reduces the organism's chances of survival; depends on environment
question
Gene Mutations
answer
Have enabled some kinds of bacteria to become resistant to certain antibiotics; antibiotics do not kill the bacteria that have the mutation
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question
Heredity
answer
The passing on of physical characteristics from parents to offspring (traits from one generation to the next)
question
Gregor Mendel
answer
Considered the father of genetics because of his work with cross-pollinating pea plants
question
Trait
answer
A specific characteristic that an organism can pass on to its offspring through its genes
question
Genetics
answer
The scientific study of heredity (what is passed down from generation to generation by DNA)
question
Fertilization
answer
Occurs when the sperm from the male connects with the egg of the female and a new organism begins to form
question
Purebred
answer
An organism that is the offspring of many generations that have the same traits.
question
F1 Offspring
answer
The "First Filial Generation" - The sons and daughters of two purebred plants that have been cross-pollinated. Mendel crossed purebred tall plants with purebred short plant, but the results was ONLY SHORT plants.
question
Filial
answer
Son or daughter of the F1 generation
question
F2 offspring
answer
The "Second Filial Generation" - Sons and daughters of cross-pollinated plants that showed traits from the original parents. Mendel allowed the fully-grown F1 plants to self-pollinate - surprisingly, the Second Filial generation were a mix of BOTH tall (3/4 th's, or 75%) and short (1/4 th, or 25%) plants. The SHORT trait had reappeared.
question
Genes (definition 1)
answer
Factors that control a trait (that are passed on from one generation to the next)
question
Alleles
answer
Different forms of a gene. Dominant traits will ALWAYS show up in offspring, and recessive traits will ONLY show up WHEN PAIRED WITH ANOTHER RECESSIVE TRAIT.
question
Dominant Allele
answer
The trait that ALWAYS shows-up in the (new/offspring) organism when the dominant allele is present (like the TALL trait in Mendel's experiments)
question
Recessive Allele
answer
A trait that is hidden whenever the dominant allele is present. This trait will ONLY show-up IF the organism does NOT have the dominant allele.
question
Hybrid
answer
An organism that has 2 different alleles for a trait - it is HETEROZYGOUS for a particular trait.
question
Probability
answer
- A number that describes how likely it is that an event will occur. - The laws of probability predict what is LIKELY to occur, NOT necessarily what WILL occur. - Mendel realized that the mathematical principles of probability could be used to predict the results of genetic crosses.
question
Punnett Square
answer
- A chart that shows all the possible combinations of alleles that can result from a genetic cross. - A visual representation of the events that occur at MEIOSIS.
question
Using a Punnett Square, you can...
answer
see the different combinations of genetic crosses that will result in the offspring as a result of traits that are passed on from the parents. Each parent contributes one allele to each offspring.
question
Phenotypes
answer
Physical appearance and visible traits in an organism
question
Genotypes
answer
An organism's genetic make-up, or allele combinations
question
Homozygous traits
answer
An organism with that has 2 IDENTICAL alleles for a trait.
question
Heterozygous traits
answer
- An organism with that has 2 DIFFERENT alleles for a trait. - Also known as "HYBRID"
question
Codominance
answer
Occurs when the alleles are NEITHER recessive or dominant, but both traits (alleles) show up in the offspring
question
Walter Sutton and his "hypothesis"
answer
- American geneticist who wanted to understand how sex cells form. - He studied grasshoppers and "hypothesized" (thought) that chromosomes were the key to understanding how offspring have the traits of their parents.
question
Sutton's Observations and Discovery
answer
- That a grasshopper had 24 chromosomes, and its offspring ALSO had exactly 24 chromosomes. - The chromosomes existed in 12 pairs, with ONE chromosome in each pair from the MALE parent and ONE chromosome from the FEMALE parent.
question
Body/Sex cells in grasshoppers
answer
Body cells of a grasshopper have 24 chromosomes, while sex cells only have 12. Also, the 24 chromosomes existed in 12 pairs.
question
Chromosome theory of inheritance
answer
- Genes are carried from parents to their offspring ON chromosomes - Alleles are literally carried ON the chromosomes of the parents and passed to the offspring.
question
Meiosis
answer
The process by which the number of chromosomes is reduced by half to form sex cells (sperm and eggs)
question
Sex cells
answer
Sperm and Eggs
question
During Meiosis...
answer
- The chromosome pairs separate and are distributed to TWO different cells. - The resulting sex cells have only HALF as many chromosomes as the other cells in the organism
question
Chromosome Pairs
answer
- Each sex cell has ONE chromosome from each original pair. - However, the offspring still ends-up with the normal number of chromosomes because it receives half from each parent. - HUMANS HAVE 23 PAIRS OF CHROMOSOMES (vs. grasshoppers who have 24 pairs)
question
Genes on Chromosomes
answer
- Chromosomes are made up of many genes joined together like beads on a string. - The chromosomes in a pair may have DIFFERENT alleles for some genes, and the SAME alleles for others.
question
20,000-25,000
answer
The number of chromosomes you have in your body, even though you only have 23 pairs
question
The Main Function of Genes
answer
- To control the production of proteins in an organism's cells - To contain the code that determines the structure of a protein.
question
Chromosomes and DNA
answer
- Chromosomes are composed mostly of DNA. - A gene is a section of a DNA molecule that contains the information to code for ONE specific protein.
question
Proteins
answer
Help to determine the size, shape, color, and many other traits of the organism
question
DNA and Nitrogen Bases
answer
DNA of made up of FOUR Nitrogen Bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). These bases form the "rungs" on the DNA ladder
question
Nitrogen pairs
answer
AT and CG
question
Gene (Definition 2)
answer
A section os a DNA molecule that contains information to code for a specific protein
question
How Many Bases a Gene May Contain
answer
A single gene on a chromosome may contain several hundred to a million or more nitrogen bases
question
The Order of Nitrogen Bases
answer
Forms a genetic code that specifies what type of proteins will be produced
question
Chain Molecules
answer
Proteins made of individual amino acids
question
Protein Synthesis
answer
- During this process, the cell uses information from a gene on a chromosome to produce a specific protein. - Takes place on the ribosomes in the cytoplasm of the cell
question
During Protein Synthesis...
answer
The cells use information from a gene on a chromosome to produce specific proteins
question
Before Protein Synthesis can take place...
answer
- A 'messenger' must first carry the genetic code from the DNA (located inside the nucleus) to the cytoplasm (located outside the nucleus). ****- This genetic "messenger" is called "RNA" (Ribonucleic acid) - ****
question
Messenger RNA
answer
Copies the coded message from the DNA in the nucleus, and carries the message to the ribosomes in the cytoplasm.
question
Transfer RNA
answer
Carries amino acids to the ribosomse and adds them to the growing proteins.
question
How many "strands" does DNA, and RNA, have?
answer
DNA has 2 strands RNA only has one strand
question
How is RNA formed?
answer
- RNA bases pair-up with DNA bases: - Guanine always pairs with Cytosine; and Adenine always pairs with Uracil. - So, RNA contains: Guanine, Cytosine, Adenine, and Uracil.
question
What id the difference between the DNA and RNA combination of "bases?"
answer
Uracil takes the place of Thymine in RNA (DNA contains: RNA contains: Guanine, Cytosine, Adenine, and Thymine. RNA contains: RNA contains: Guanine, Cytosine, Adenine, and Uracil.)
question
Protein Synthesis, Step One
answer
DNA provides code to form messenger RNA
question
Protein Synthesis, Step Two
answer
Messenger RNA attaches to Ribosome
question
Protein Synthesis, Step Three
answer
Transfer RNA attaches to Messenger RNA
question
Protein Synthesis, Step Four
answer
Protein Production Continues
question
Mutations
answer
Can cause a cell to produce an incorrect protein during protein synthesis. The organism's trait, or phenotype, may be different from what it normally would have been.
question
Mutation in Body Cell
answer
The mutation will not be passed on to the offspring
question
Mutation in a Sex Cell
answer
The mutation can be passed on the offspring
question
Where Mutations occur
answer
DNA replication process
question
Chromosomes incorrectly separating during Meiosis
answer
When this mutation occurs, a cell can end up with too many or too few chromosomes
question
A Mutation is harmful if...
answer
It reduces the organism's chances of survival; depends on environment
question
Gene Mutations
answer
Have enabled some kinds of bacteria to become resistant to certain antibiotics; antibiotics do not kill the bacteria that have the mutation