More Biology

Front 1

describe the "double-helix" model of DNA structure

Back 1

two complementary strands of nucleotides are twisted into a spiral around an imaginary axis, like a winding staircase. The two strands are held together by hydrogen bonds.

Front 2

define "base pair" and explain how they form the structure of DNA

Back 2

"base pair" refers to two bases held together by hydrogen bonds in a DNA molecule. These bases hold a tremendous amount of information stored in the order of the bases along the DNA molecule-- in the DNA sequence

Front 3

explain how molecules of DNA and RNA are similar and how they are different

Back 3

DNA; double-stranded structure, two polynucleotide strands wound into a helix. Deoxyribose sugar. A, G, C, T nucleotides. Stores genetic info. Highly stable in most cells. Located in the nucleus, chloroplasts and mitochondria in eukaryotes; cytosol in prokaryotes.

RNA; single-stranded polynucleotide, may fold back on itself. Ribose sugar. A,G,C,U nucleotides. Expresses genetic info by directing the manufacture to a specific protein. Generally much less stable. Located in the same locations as DNA

Front 4

Definition of gene

Back 4

the smallest unit of DNA that governs a genetic characteristic and contains the code for the synthesis of a protein or an RNA molecule. Genes a located on chromosomes.

Front 5

Definition of genome

Back 5

All the DNA of an organism, including all its genes; in eukaryotes, the term refers to the DNA in a haploid set of chromosomes such as that found in a sperm or egg.

Front 6

Define chromosome

Back 6

A threadlike structure composed of a single DNA molecule packaged with proteins. Chromosomes achieve the highest level of compaction when prophase begins during mitosis or meiosis.

Front 7

Describe the structure of a nucleotide, and how DNA nucleotides are similar/different from RNA nucleotides

Back 7

Nucleotide in DNA: A (adenine), G (guanine), C (cytosine), T (thymine)

in RNA: A (adenine), C (cytosine), G (guanine), U (uracil)

Front 8

Discuss how genetic information is stored in a molecule of DNA

Back 8

it contains the genetic instructions for the function and development of living things

Front 9

Describe how exact copies of an entire DNA molecule are made during replication; name the enzyme catalyst of DNA replication and state the chemical reaction that is catalyzed by this enzyme

Back 9

Producing exact copies of DNA ensures that when a cell divides, the offspring will receive the same genetic information as the parent cell. DNA polymerase enzymes can then bind to the open half-strands.

Front 10

explain why replication is known as a "semi-conservative" process

Back 10

because one "old" strand (the template strand) is retained, or conserved, in each new double helix

Front 11

explain the role of a gene in determining a trait/characteristic (phenotype) of an organism

Back 11

genes are turned off/on selectively in response to short-term changes in environmental conditions

Front 12

discuss what happens when replication errors change the order of nucleotides in a gene

Back 12

DNA repair enzymes usually detect and fix mismatch errors before the cells DNA is replicated again. If the mismatch is not repaired before the next round of DNA replication, a mutation occurs.

Front 13

describe the structure and function of the three types of RNA molecules that play a role in protein synthesis: mRNA, rRNA, and tRNA molecules

Back 13

mRNA: Messenger RNA, its function is to deliver genetic info from DNA to the ribosomes.

rRNA: Ribosomal RNA, important component to ribosomes

tRNA: Transfer RNA, transfers amino acid specified by mRNA to the ribosome during protein synthesis

Front 14

describe how an mRNA copy of a gene is made by transcription; name the enzyme catalyst of transcription

Back 14

the synthesis of an RNA molecule from a DNA template. The first of two major steps in the process by which genes specify proteins; it produces mRNA, tRNA, rRNA

Front 15

explain the role of promoter and terminator sequences in the DNA sequence of a gene

Back 15

A promoter is a region of DNA where RNA polymerase binds to initiatetranscription.

A terminator is a sequence of DNA that causes RNA polymerase to terminate transcription.

Front 16

Given a sequence of nucleotides in the DNA of a gene, demonstrate the ability to transcribe it into an mRNA transcript

Back 16

example: DNA is ATGCGCAGTTATTGCGAT

then mRNA is UACGCGUCAAUAACGCUA

Front 17

define "codon"

Back 17

a sequence of three nitrogenous bases in an mRNA molecule. Each codon specifies either a particular amino acid or a signal to start or stop the translation of a protein.

Front 18

define and differentiate between a codon in mRNA and an anticodon in a tRNA molecule

Back 18

A codon is a three-base sequence (three nitrogen bases in a row) on mRNA. It calls for a specific amino acid to be brought to the growing polypeptide. An anticodon is a three-base sequence on tRNA. It matches the codon.

Front 19

explain how ribosomes interpret codons in the mRNA to produce a chain of amino acids during translation; describe the role of tRNA molecules and amino acids in this process

Back 19

the mRNA code is turned into the precise sequence of amino acids that become covalently linked to form the protein product. Each type of tRNA specializes in binding to one specific amino acid, and it recognizes and pairs with specific codons in the mRNA. mRNA binding site is termed the anticodon.

Front 20

discuss how amino acids are linked by peptide bonds to form the primary structure (simple chain of amino acids) of the protein produced by translation of the mRNA

Back 20

ribosomes are responsible for linking the amino acids together, using mRNA as a template. each tRNA carries a specific amino acid and has a specific anticodon sequence that binds to a complementary three-base sequence in the mRNA

Front 21

explain how protein secondary and tertiary structures are formed when amino acids in different parts of the chain are attracted to one another, form bonds, and cause the protein to "fold up"

Back 21

Primary structure is the sequence of amino acids, translation, going from mRNA to the ribosome and the tRNA links those up.

Secondary structure is due to the interactions of the peptide backbone

Front 22

consider the effect that mutations in the DNA sequence of a gene have on the synthesis of a protein from that gene

Back 22

major types of mutations that alter a genes DNA sequence: substitutions, insertions, and deletions.

substitutions is where one base is substituted for another; T being replaced to a C.

deletions/insertions is where a base is inserted or deleted from the sequence. single-base insertions/deletions cause a genetic frameshift. which alters the results of a protein so severely it fails to function.

Front 23

discuss the relationship between the information in the DNA of a gene (nucleotide sequence, genotype) and the trait/characteristic that results from expression of that gene (phenotype)

Back 23

in gene expression, a gene is transcribed and its mRNA is translated into a functional protein that has an effect on phenotype. cells process information from a variety of signals and that information affects which genes are expressed.

(phenotype: hair/eye color

genotype: traits)

Front 24

explain why and how cells control the expression of genes

Back 24

gene expression - cells recieve signals also from the organisms internal environment (like blood sugar) and external environment (sunlight in plants).

Front 25

explain the six models of gene expression regulation. which is the most common

Back 25

1.) tight packaging of DNA prevents it from being expressed.

2.) regulation of transcription conserves resources.

3.) breakdown of mRNA prevents wasteful synthesis of proteins.

4.) regulation of translation keeps mRNA ready for rapid protein synthesis when needed.

5.) proteins can be directly regulated by modification following translation.

6.) regulation of protein breakdown conserves resources and prevents damage.