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9th Science > Science Semester 2 Final > Flashcards

Science Semester 2 Final Flashcards

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1
Q

What is DNA made of?

A

Nucleotides

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2
Q

Structure of a Nucleotide (DNA)

A

Deoxyribose sugar connects to phosphate and a nitrogen base (adenine, guanine, cytosine, or thymine)

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3
Q

Purines

A

Big base. Adenine and Guanine.

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4
Q

Pyrimidines

A

Small base. Cytosine and Thymine (and Uracil).

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5
Q

What are the differences between DNA and RNA?

A

DNA: Nitrogenous bases are A, T, C, and G. Uses deoxyribose sugar. Double helix.

RNA: Nitrogenous bases are A, U (Uracil), C, and G. Uses ribose sugar. Single strand.

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6
Q

Complementary Base Pairs

A

Adenine with Thymine. Cytosine with Guanine.

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7
Q

DNA Replication Process

A

Enzyme Helicase unzips the DNA into two strands. Enzyme DNA Polymerase adds complementary nucleotides to the template strands. It only adds on the free 3’ end of the template strand, meaning DNA forms in the 5’ to 3’ direction only. Two identical DNA molecules are formed, each with an “old” strand and a “new” strand. (Which is why it’s semi-conservative replication)

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8
Q

Semi-Conservative Replication: Basic Process

A

Each parent strand is now a template that determines the order of the new bases. Forms a “complementary” strand to original strand. The two new double helixes are each a combination of one “old” strand and one “new” DNA strand.

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9
Q

Leading Strand

A

New strand made towards the replication fork. Needs one RNA primer made by Primase. The leading strand is made continuously.

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10
Q

Lagging Strand

A

New strand made away from the replication fork. Replicates discontinuously. Creates fragments of DNA which are joined together by DNA Ligase, Needs many RNA primers made by Primase.

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11
Q

What are the inputs and outputs of transcription? What’s its location?

A

Input: DNA
Output: mRNA
Location: Nucleus

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12
Q

What are the inputs and outputs of translation? What’s its location?

A

Input: mRNA
Output: Protein
Location: Cytoplasm/Ribosome

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13
Q

Transcription Process

A
  1. RNA Polymerase binds to the DNA Promoter where transcription is to begin and unzips the gene that needs to be copied (“TATA box”). 2. RNA Polymerase uses complementary base-pairing rules to match RNA nucleotides with the exposed DNA nucleotides. 3. The completed mRNA molecule is released. 4. DNA zips back up and the mRNA leaves the nucleus and enters the cytoplasm.
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14
Q

Translation Process

A
  1. mRNA attaches to the small subunit of the ribosome. 2. Ribosome reads the mRNA codons in the 5’ to 3’ direction; starting at codon AUG. 3. tRNA molecules act like taxis to pick up and drop off the amino acids that match with the current codon being read off the mRNA. 4. tRNA’s continue to drop off amino acids, and the ribosome binds the amino acids together with peptide bonds
    When the “stop codon” is reached, the ribosome releases the completed protein.
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15
Q

Codon

A

A set of three nucleotides on mRNA made of the bases A, U, G, C.

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16
Q

Anticodon

A

The complementary three nucleotides that tRNA carries.

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17
Q

Where do the codon and anticodon meet?

A

On the ribosome

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18
Q

mRNA

A

Messenger RNA. Copies instructions in DNA and carries these to ribosomes in the cytoplasm.

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19
Q

tRNA

A

Transfer RNA. Carries amino acids to the ribosomes and mRNA.

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20
Q

Transcription Purpose

A

Carry the code/instructions out of the nucleus

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21
Q

Translation Purpose

A

Read/follow the instructions on the mRNA to make a protein

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22
Q

Somatic Cells

A

“Body” cells. Diploid.

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23
Q

Diploid Cells

A

A cell containing two sets of chromosomes

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24
Q

Gametes

A

“Sex” cells (egg or sperm cells). Haploid.

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25
Haploid Cells
A cell containing only one set of chromosomes
26
Dominant
Traits that are always expressed if the allele is present.
27
Recessive
Traits that are hidden whenever a dominant allele is present. Only expressed when both alleles are recessive
28
Homozygous
Refers to allele pair in which the two alleles are identical. Also called purebred. (Ex. AA or aa)
29
Heterozygous
Refers to allele pair in which the two alleles are different. Also called hybrid. (Ex. Aa)
30
Genotype
The genetic makeup of an organism. Ex: AA
31
Phenotype
The external appearance of an organism that is determined by the individual’s genotype. Ex: white flowers
32
Gregor Mendel
Austrian monk who used pea plants to learn about genetics. He is known as the “Father of Genetics”. Came up with the three laws of inheritance
33
Mendel’s Experiments Three Main Points
1. Had control over breeding - Mendel used pea plants that typically self-pollinate. 2. Used only purebred plants. 3. Observed “either-or” traits- included pea shape, pea color, and plant height
34
Law of Dominance
Some alleles are dominant others are recessive.
35
Law of Segregation
When chromosomes separate in meiosis, each gamete (egg or sperm) will receive only one chromosome from each pair. (Ex: If a man has alleles for brown and blonde hair Bb), his sperm cells can contain the allele for brown hair (B) OR the allele for blonde hair (b). Each sperm only gets ONE of the alleles.)
36
Law of Independent Assortment
The assortment of chromosomes for one trait doesn’t affect the assortment of chromosomes for another trait (the inheritance of one trait doesn’t affect the inheritance of another trait). Therefore, any combination of maternal and paternal chromosomes could be passe on because homologous chromosomes line up randomly during metaphase.
37
Incomplete Dominance
The heterozygous phenotype is somewhere between the two homozygous phenotypes. Neither allele is completely dominant or recessive. Ex: Red and white flowers make pink flowers
38
Codominance (Two examples)
Both traits are fully and separately expressed. Ex: Red and white flowers make red and white speckled flowers. Ex: Blood type (AB blood is fully A and fully B)
39
Multiple Alleles
Having more than two alleles for one gene. Ex: alleles for blood type are A, B, and i.
40
Polygenic Inheritance
A trait produced by two or more genes. Usually shows a range in phenotype. Ex: skin color, eye color, height, personality
41
Sex-Linked Genes Definition
Genes on sex chromosomes
42
How many genes do the X vs Y chromosome carry?
X chromosome contains many genes that affect many traits. Y chromosome carries few genes
43
X-Linked Genes
Females inherit gene as normal and the principle of dominance applies. Males inherit the gene on the X, but not the Y. Since males have only one X, they express the trait whether it’s dominant or recessive.
44
Females vs Males Chromosomes
Female: XX Male: XY
45
Linked Genes
Genes that are physically located on the same chromosome will be inherited together. Linked genes can be separated or broken apart during crossing over.
46
Chromosome Theory of Inheritance
A theory that states that genes are located on chromosomes, and these chromosomes are responsible for the inheritance of traits.
47
Gene Mutations
Happen during DNA replication = A change to the original DNA sequence
48
Point Mutation
Gene mutation. Substitutes one nucleotide for another.
49
Frameshift Mutations
Gene mutation. The insertion or deletion of a nucleotide. These will affect all the codons that come after the insertion/deletion.
50
Chromosome Mutation
Happen during meiosis = Changes the number or location of genes
51
Duplication
Chromosome mutation. Changes the size of chromosomes and results in multiple copies of a single gene.
52
Translocation
Chromosome mutation. Pieces of non-homologous chromosomes exchange segments (during crossing over)
53
Nondisjunction
Chromosome mutation. Chromosomes do not separate correctly during anaphase, resulting in one or three chromosomes rather than two per cell
54
Pedigree: How to Determine Dominant or Recessive
1. Look for two parents that are the same shade that are the same shade that have a child who is different from them. 2. Label that child homozygous recessive (rr) and the parents heterozygous (Rr) 3. -If the child was shaded, the pedigree is tracking a Autosomal Recessive Trait. -If the parents were shaded, the pedigree is tracking a Autosomal Dominant Trait.
55
Pedigree: How to Determine Autosomal or X-Linked
Do affected males have affected sons? Yes - Autosomal No - X-linked Is the trait equally distributed among both males and females?* Yes - (probably) autosomal No - X-linked (recessive) *only applies to recessive x-linked
56
What types of mutations do and don’t get passed on?
Germline mutations (that occur in gametes - eggs and sperm) can be passed on to offspring. Somatic mutations (that occur in body cells) are not.
57
Cloning
Identical copy of a gene of an entire organism.
58
Gene Therapy
Insert a normal gene into an absent or abnormal gene
59
Stem Cells
Undifferentiated cells that have the potential to become anything
60
Selective Breeding
Artificially breeding organisms with a desired traits
61
Hybridization
Breeding organisms that show two traits in order in order to produce offspring that express both those traits (ex. zonkey = zebra + donkey)
62
Pros of genetic engineering (4)
1. The development of plants that grow quicker and have natural insecticides. 2. The development of animals that are bigger and faster growing. 3. The development of bacteria that produce human insulin and human growth hormones 4. Transplant copies of normal genes into the cells of people suffering from genetically carried diseases
63
Cons of genetic engineering (4)
1. Food may become less nutritious. 2. Risky pathogens develop as viruses and bacteria adapt to environments. 3. Negative side effects from gene transfers 4. Unfavorable diversity as genetically-modified animals/crops outperform natural ones
64
Darwin’s Observations and Conclusions
English naturalist who went on a voyage to the Galapagos Islands. He observed adaptations of plants and animals that inhabited diverse environments. He developed his theory of natural selection to serve as the mechanism for how evolution occurs.
65
Evolution
The process of biological changes that make descendants differ from ancestors. Change of traits/genes over time
66
Natural Selection
Some organisms will survive and reproduce better than others, causing changes in the population over time by acting on traits that are heritable.
67
What are the principles of natural selection? (4)
1. Variation: Differences in the physical traits of organisms 2. Overproduction of Offspring: Production of more individuals than can be supported by the environment which leads to a struggle for existence among individuals. 3. Adaptation: Individuals who inherit characteristics that are most fit to their environment are more likely to have more offspring. 4. Descent with Modification: Over time these adaptations will increase the population
68
Adaptation
Any heritable trait that helps an organism, such as a plant or animal, survive and reproduce in its environment
69
Speciation
Forming of a new species by evolution from pre-existing species - when gene pools are no longer able to reproduce
70
Extinction
Elimination of a species
71
Stabilizing Selection
Eliminates extreme expressions of a trait where the average expression leads to higher fitness
72
Directional Selection
Increases the expression of an extreme version of a trait in a population
73
Disruptive Selection
A process that splits a population into two groups; removes individuals with average traits and favors the extremes
74
Analogous Structures
Similar function, different structure. Evolved similar structures due to living in similar environments, not due to ancestral relatedness.
75
Vestigial Structures
Structures with little or no function to the organism. Remnants of structures that had important functions in ancestors of the species.
76
Homologous Structures
Similar structure, different function. Similar characteristics resulting from common ancestry.
77
Embryology. What is it? How is it evidence for evolution?
The study of embryonic development of organisms. The embryos of vertebrates are very similar in appearance early in development but may grow into different structures in the adult form. This suggests common ancestry among vertebrates.

9th Science (16 decks)

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