Science study for exam

Nucleic Acids

The macromolecule that carries our genetic information (DNA & RNA)

Gene

A section of DNA that contains instructions for making protein

Nucleotide

The monomer of nucleic acids

Double Helix

Shape of DNA, like a twisted ladder

Hydrogen Bonds

Weak bonds that that hold the nitrogen bases together

Covalent Bonds

Strong bonds that hold the sugar-phosphate backbone together

Complementary Base Pairs (DNA)

A-T, C-G

Complementary Base Pairs (RNA)

A-U, C-G

DNA

Deoxyribonucleic Acid

RNA

Ribonucleic Acid

Chromosomes

Tightly coiled strands of DNA

DNA Replication

The process of making an identical copy of a strand of DNA

Semi- Conservative Replication

Each new DNA double-helix is made of 1 strand from the original DNA molecule & 1 new complementary strand

Protein Synthesis

The process of reading the instructions in DNA to make a polypeptide

Polypeptide

A chain of amino acids; can bind to others & fold into a protein

Central Dogma of Genetics

DNA -\> RNA -\> Protein

Messenger RNA (mRNA)

Copies instructions in DNA & carries these to the ribosomes in the cytoplasm

Transfer RNA (tRNA)

Carries amino acids to the ribosome & mRNA

Ribosomal RNA (rRNA)

Composes the ribosome

Transcription

The process of converting DNA to mRNA

Translation

The process of converting mRNA to a polypeptide

Genetic Code

Code of instructions for how to make proteins

Codon

A set of three (3) nucleotides of mRNA

Anticodon

A set of three (3) complementary tRNA nucleotides

Amino Acid

Monomer of proteins; held together by peptide bonds

Epigenetics

The study of changes in gene expression that are heritable

Mutation

A change in a DNA sequence

Somatic Cells

Body cells that are diploid (2n)

Gametes

Sex cells that are haploid (n)

Diploid

A cell with 2 full sets of chromosomes; 1 from each biological parent

Haploid

A cell with 1 full set of chromosomes; a combination of genes from both biological parents

Autosomes

Chromosomes that carry traits that make you who you are. Chromosome pairs 1 - 22

Sex Chromosomes

Chromosomes that carry traits that make you who you are & determine your biological sex. Chromosome pair 23

Karyotype

A diagram that shows the number & appearance of chromosomes in a cell

Meiosis

The process of cell division that makes gametes

Fertilization

The fusion of egg & sperm cells to form a zygote

Zygote

A fertilized egg cell

Homologous Chromosomes

Chromosome pairs that have the same types of genes in the similar locations

Sister Chromatids

Two identical copies of the same chromosome

Meiosis I

The separation of homologous chromosomes (Diploid to haploid)

Meiosis II

The separation of sister chromatids (Duplicated chromosomes to individual chromatids)

Interphase

The growth phase of the cell cycle

Prophase I

Nuclear membrane breaks down, centrioles separate & make spindle fibers, homologous chromosomes pair up & become visible

Tetrad

A cluster of 4 chromatids

Crossing over

Process in which homologous chromosomes exchange pieces of DNA during meiosis

Metaphase I

Homologous chromosomes are lined up in the middle of the cell in pairs

Anaphase I

Homologous chromosome pairs separate. 1 chromosome (2 sister chromatids) is pulled to each side of the cell

Telophase I

Chromosomes gather at poles, nuclear membrane may re-form, cytokinesis happens. End result is 2 haploid daughter cells with duplicated chromosomes that are different from the original cell.

Cytokinesis

The division of the cytoplasm

Prophase II

Spindle fibers form & attach to the centromeres of the sister chromatids. Nuclear membrane breaks down if it re-formed.

Metaphase II

Sister chromatids line up in the middle of the cell single file

Anaphase II

Sister chromatids separate & are pulled away from each other to opposite sides of the cells

Telophase II

Nuclear membranes form around each set of chromosomes, spindle fibers dissolve, cytokinesis happens. End result is 4 genetically unique, haploid daughter cells

Gene

A section of DNA with instructions for making a protein

Alleles

Different versions of the same gene

Gregor Mendel

Austrian monk who used pea plants to study genetics. Known as a the "Father of Genetics".

Purebred

A type of organism whose ancestors are genetically identical

Cross

Mating of two (2) organisms

Homozygous

Two (2) of the same alleles for a trait (AA or aa)

Heterozygous

Two (2) different alleles for a trait (Aa)

Law of Dominance

A dominant allele will express itself over a recessive allele

Dominant

If present, this allele will have its trait expressed

Recessive

This allele will only be expressed if the dominant allele is not present

Genotype

The actual alleles inherited

Phenotype

The physical traits seen in an organism

Law of Segregation

When chromosomes separate in meiosis, each gamete will receive only one (1) chromosome from each pair

Law of Independent Assortment

The assortment of chromosomes for one (1) trait does not affect the assortment of chromosomes for another trait

Punnett Square

A diagram that shows the probability of inheriting traits from parents with certain genes

Monohybrid Cross

A cross between two (2) organisms looking at one (1) trait

Chromosome Theory of Inheritance

Genes are located on chromosomes & the behavior of chromosomes during meiosis causes the inheritance patterns we observe

Incomplete Dominance

The heterozygous phenotype is somewhere between the 2 homozygous phenotypes

Codominance

Both traits are fully & separately expressed

Multiple Alleles

Having more than 2 alleles for a single gene

Polygenic Inheritance

A trait produced by 2 or more genes

Epistasis

When 1 gene overshadows all the others

Linked Genes

Genes that are physically located on the same chromosome that will be inherited together

Autosomes

Chromosome pairs 1-22

Sex Chromosomes

The last (23rd) pair of chromosomes

XX

Female sex chromosomes

XY

Male sex chromosomes

Sex-linked genes

Genes located on the sex chromosomes

Carrier

Someone who carries the recessive trait but does not show it due to having a dominant X to mask it

Mutation

Any change in a DNA sequence

Somatic Mutations

Occur in body cells & are passed on by mitosis causing cancer

Germ Line Mutations

Occur in cells that create gametes & are passed on by meiosis causing offspring with mutations

Mutagens

Chemicals that can cause DNA mutations

Gene Mutations

Happen during DNA replication & change the original DNA sequence

Chromosome Mutations

Happen during meiosis & change the number or location of genes

Point Mutation

A gene mutation where one nucleotide is substituted for another

Frameshift Mutation

A gene mutation where a nucleotide is inserted or deleted from a DNA sequence

Duplication

A chromosome mutation that changes the size of chromosomes & results in multiple copies of a single gene

Translocation

A chromosome mutation where pieces of non-homologous chromosomes exchange segments during crossing over

Nondisjunction

A chromosome mutation where chromosomes do not separate correctly during anaphase, resulting in 1 or 3 chromosomes rather than 2 per cell

Autosomal Recessive Disorders

Caused by the presence of 2 recessive alleles on autosomes (Ex: Sickle Cell Anemia)

Autosomal Dominant Disorders

Caused by the presence of at least 1 dominant allele on autosomes (Ex: Huntington's Disease)

Sex-Linked Disorders

Caused by the presence of an allele on the X chromosome (Ex: Hemophilia)

Autosomal Chromosome Disorders

Often caused by nondisjunction of autosomes (Ex: Down Syndrome)

Sex Chromosome Disorders

Often caused by nondisjunction of sex chromosomes (Ex: Turner's Syndrome)

Pedigree

A chart used to trace the phenotypes & genotypes in a family to determine whether people carry diseases or traits

Biotechnology

Any technology used to change the genetic makeup of living things to make products