Unit 1 Biology Study Guide

Front 1

Eukaryote

Back 1

- cells contain their genetic material inside a nucleus
- includes large, complex organisms
- nucleus separates transcription and translation
- undergoes mitosis and meiosis

Front 2

Nucleotide

Back 2

- basic chemical unit in nucleic acids
- four nucleotides make up DNA
- if nucleotide sequence altered, protein may be altered
- purines = adenine and guanine
- pyrimidines = cytosine and thymine

Front 3

Base Pairs

Back 3

- pair of nucleotides form by complementary base pairing of a purine and pyrimidine
- A --> T
- G --> C
- surfaces are chemically distinct, allowing other specific molecules to bind to them

Front 4

Chargaff's Rule

Back 4

- A = T and G = C
- Total # of Purines = Total # of Pyrimidines

Front 5

Double Helix

Back 5

- stores an organism's genetic information
- right-handed
- antiparallel
- minor and major grooves
- sugar-phosphate "backbones" held together by hydrogen bonding
- complimentary base pairing
- 5' end = free, phosphate
- 3' end = free, hydroxyl

Front 6

Genome

Back 6

- the full DNA sequence of an organism
- divided into pieces called chromosomes
- haploid set of chromosomes in a gamete
- remains constant, but gene expression varies in space and time

Front 7

Eukaryotic Genome

Back 7

- larger --> more protein-coding genes
- contain numerous repetitive DNA sequences that do not code for polypeptides

Front 8

Chromosomes

Back 8

- the DNA molecule that contains most or all of the genetic information of a cell or virus
- chromosome number and structure can change without having a major effect on genome size or content
- has an ori, centromere region, and telomeric sequence to maintain chromosome integrity

Front 9

Barr body

Back 9

- one of X chromosomes in each cell of female is transcriptionally inactivated in early embryonic development
- reason why transcription is nearly same in both males and females

Front 10

Sister Chromatids

Back 10

- each of a pair of newly replicated chromatid
- after replication --> held together by cohesin
- by metaphase --> cohesin removed, except for at centromere
- by anaphase --> the enzyme separase hydrolyzes the remaining cohesin and chromosome separate

Front 11

Haploid

Back 11

- having a chromosome complement consisting of just one copy of each chromosome
- two haploid gametes fuse to form a zygote in fertilization

Front 12

Diploid

Back 12

- having a chromosome complement consisting of two copies of each chromosome
- zygotes are diploid --> may divide either by meiosis or mitosis --> new mature organism develops that is capable of sexual reproduction

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Aneuploidy

Back 13

- a condition in which one or more chromosomes or pieces of chromosomes are either lacking or present in excess
- trisomic of chromosome 21 = Down syndrome

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Polyploidy

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- the possession of more than two entire sets of chromosomes
- may be produced by artificial breeding or by natural accidents
- desirable trait in plants because leads to more robust plants

Front 15

Duplication

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- a mutation in which a segment of a chromosome is duplicated, often by the attachment of a segment lost from its homolog
- would arise if homologous chromosomes broke at different positions and reconnected to the wrong partners

Front 16

Deletion

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- result form the removal of part of the genetic material
- consequences can be severe unless they affect noncoding DNA or unnecessary genes

Front 17

Inversion

Back 17

- a segment of DNA may be removed and reinserted into the same location in chromosome, but "flipped" end over so that it runs in the opposite direction
- can result from breaking and rejoining of chromosomes

Front 18

Reciprocal Translocation

Back 18

- interchange of chromosome segments between two non-homologous chromosomes

Front 19

Gene

Back 19

- a unit of genetic function which carries the information for a single polypeptide or RNA

Front 20

One-gene, One-enzyme Relationship

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- genes act through the production of enzymes, with each gene responsible for producing a single enzyme that in turn effects a single step in a metabolic pathway

Front 21

One-gene, One-polypeptide Relationship

Back 21

- the function of a gene is to inform the production of a single, specific polypeptide

Front 22

Transcription

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- the information in a DNA sequence is copied into a complementary RNA sequence

Front 23

Translation

Back 23

- the process by which a sequence of nucleotide triplets in a mRNA gives rise to a specific sequence of amino acids during protein synthesis

Front 24

Amino Acid

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- an organic compound containing both NH2 and COOH groups
- proteins are polymers of amino acids

Front 25

Adapter Molecule

Back 25

- contains an anticodon complementary to the codon in mRNA
- binds a specific amino acid and recognizes a specific sequence of nucleotides

Front 26

Protein

Back 26

- long-chain polymer of amino acids with twenty different common side chains

Front 27

Ribosome

Back 27

- a small particle in the cell that is the site of protein synthesis

Front 28

Polypeptide

Back 28

- a large molecule made up of many amino acids joined by peptide linkages
- large polypeptides are called proteins

Front 29

Messenger RNA (mRNA)

Back 29

- carries a copy of a gene sequence in DNA to the site of protein synthesis at the ribosome
- must be translated in the correct reading frame

Front 30

Ribosomal RNA (rRNA)

Back 30

- catalyzes peptide bond formation and provides structural framework for the ribosome

Front 31

Transfer (tRNA)

Back 31

- carries amino acids to the ribosome for assembly into polypeptides
- charged tRNA will deliver appropriate amino acid to join the elongating polypeptide product of translation
- must read mRNA codons correctly
- must deliver the amino acids that correspond to each mRNA codon

Front 32

microRNA

Back 32

- a small, noncoding RNA molecule that binds to mRNA to inhibit its translation
- important regulators of gene expression

Front 33

RNA Polymerase II

Back 33

- enzyme in eukaryotic cells that catalyzes the transcription of DNA to synthesis precursors of mRNA, most snRNA, and microRNA

Front 34

Transcription Factors

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- binds to specific DNA sequences, thereby controlling the movement of genetic information from DNA to mRNA
- allows RNA Polymerase II to perform transcription

Front 35

TATA Box

Back 35

- a promoter DNA sequence crucial in forming the transcription intiation complex

Front 36

Exon

Back 36

- portion of DNA molecule that codes for part of a polypeptide
- expressed regions
- interspersed with the coding sequences

Front 37

Intron

Back 37

- portion of a coding region in gene that is transcribed into pre-mRNA but is spliced out prior to translation
- intervening regions
- interrupt, but do not scramble DNA sequence

Front 38

Splicing

Back 38

- transcripts of introns are excised through the action of snRNPs
- last stage of RNA processing in eukaryotes
- increases protein diversity

Front 39

Spliceosome

Back 39

- result of binding of snRNPs to consensus sequences bordering the introns on the pre-mRNA
- series of proteins binding

Front 40

Start Codon

Back 40

- the mRNA triplet (AUG) that acts as a signal for the beginning of translation at the ribosome
- contains three consecutive nucleotides
- determines reading frame

Front 41

Initiator tRNA

Back 41

- initiates protein synthesis by binding to the amino acid methionine and delivering it to the small ribosomal unit
- employed in initiation step of protein synthesis
- attaches to ribosome's P site

Front 42

Stop Codon

Back 42

- any of the three mRNA codons that signal the end of protein translation at the ribosome
- UAG, UGA, UAA

Front 43

Epigenetics

Back 43

- the scientific study of changes in the expression of a gene or set of genes that occur without change in the DNA sequence
- changes are reversible, but sometimes stable and hereditary
- includes DNA methylation and chromosomal protein alterations

Front 44

Histones

Back 44

- DNA is wrapped around it to produce chromatin
- forms core of nucleosome
- the structural unit of a eukaryotic chromosome

Front 45

Cytosine Methylation

Back 45

- impedes transcription
- turn genes "off"
- important for transposon silencing

Front 46

Transposon

Back 46

- sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell

Front 47

Zygote

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- the cell created by the union of two games, in which the gamete nuclei are also fused
- earliest stage of the diploid generations
- result of fertilization

Front 48

DNA Polymerase

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- any of a group of enzyme that catalyze the formation of DNA strands from a DNA template

Front 49

Carl Linnaeus (1707-1778)

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- father of taxonomy
- established conventions for naming of living organisms using binomial nomenclature
- developed a hierarchical system of classification of organisms

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Gregor Mendel (1822-1884)

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- father of modern genetics
- demonstrated that the inheritance of certain traits in pea plants follows particular patterns --> laws of Mendelian inheritance

Front 51

Charles Darwin (1809-1882)

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- theory of natural selection
- all life is a continuous struggle in which on the fittest can survive
- descent with modification
- Origin of Species --> theory of evolution

Front 52

Watson and Crick (1953)

Back 52

- described the double helix structure of DNA
- the solution to the structure of DNA achieved through model building
- structure is double-stranded, right-handed, antiparallel, and outer edges of nitrogenous bases are exposed in major and minor grooves

Front 53

Beadle and Tatum

Back 53

- worked to determine whether each gene determines an enzyme in a biochemical pathway
- confirmed Garrod's one-gene, one-enzyme hypothesis
- if an organisms cannot convert one particular compound to another, it lacks an enzyme required for conversion

Front 54

Gene Structure

Back 54

- coding region (makes structure)
- regulatory region (enhancers, promoter)

Front 55

DNA Sequences Act As:

Back 55

- binding sites for proteins
- a template for RNA production
- signals for RNA processing

Front 56

DNA Methylation

Back 56

- play major role in cancer

Front 57

Promoter

Back 57

- special sequence of DNA to which RNA Polymerase binds very tightly
- tells where to start transcription and which strand of DNA to transcribe

Front 58

Mendelian Laws of Inheritance

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- every individual possesses a pair of alleles passed down by each parent
- separate genes of separate traits are passed down independently of one another

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Enhancer

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- element that, upon binding with transcription factors, can enhance transcription
- transcription factors = transcriptional activators

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Silencer

Back 60

- element that, upon binding with transcription factors, can repress transcription.
- transcription factors = repressors

Front 61

Response Element

Back 61

- recognition site of certain transcription factors

Front 62

Transcriptional Region

Back 62

- part of DNA to be transcribed into RNA molecule

Front 63

Regulatory Region

Back 63

- trans-regulatory = DNA sequences that encode transcription factors
- cis-regulatory = binding sites of transcription factors that can affect transcription

Front 64

Transcriptional Region

Back 64

- part of DNA to be transcribed into RNA molecule

Front 65

Regulatory Region

Back 65

- trans-regulatory = DNA sequences that encode transcription factors
- cis-regulatory = binding sites of transcription factors that can affect transcription