9th Grade Science Final Flashcards
Describe the study of Ecology
Scientific study of interactions among organisms and between organisms and their physical environment.
What are biotic factors?
- Biological influences on organisms
- any living part of the environment with which an organism might interact
Abiotic Factors
- Physical components of an ecosystem
- any non living part of the environment (eg. sunlight, heat, precipitation)
Primary producers
The first producers of energy-rich compounds that are later used by other organisms
Methods used to study ecology.
Observation
Experimentation
Modeling
How do consumers obtain energy?
They acquire energy from other organisms-by ingesting them in one way or another. They cannot directly harness energy from the environment.
Carnivors
Kill and eat each other
Scavengers
Animals that consume carcasses of other animals that have been killed by predators or have died from other causes
Detritivores
Feed on detritus particles
Eg. Shrimp, crabs, snails
Omnivores
Diets include both plants and animals
How do humans activities affect the environment?
Humans affect environments through agriculture, development and industry in ways that have an impact on the quality of Earth’s natural resources (ie soil, water, and atmosphere).
Know the Water Cycle
Know the nutrient cycle
Role of DNA in heredity
-DNA makes up genes that must be capable of storing, copying, and transmitting the genetic information in a cell. This information is passed on.
What are the chemical components of DNA?
- DNA is a nuclei acid made up of nucleotides joined into long strands or chains by covalent bonds.
- It is made up of nitrogenous bases (adenine, guanine, cytosine, and thymine)
Describe the events of DNA replication
- DNA molecule produces two new complementary strands.
- Each strand of complementary strands
- Each strand of the double helix serves as a template for the new strand
- The principal enzyme involve in DNA replication is DNA polymera
DNA polymerase
An enzyme that joins individual nucleotides to produce a new strand of DNA
The difference between Prokaryotic DNA Replication and Eukaryotic DNA Replication
Prokaryotic-most start from a single point and proceeds in two directions until completely copied
Eukaryotic-may begin at dozens or even hundreds of places on DNA molecule, proceeding in both directions
Telomeres
Tips of eukaryotic chromosomes (tips are difficult to replicate, cells use special enzymes called telomerase)
Double Helix Model
Explains Chargaff’s rule of base pairing and how the two strands of DNA are held together
- Anitparallel strands- the two strands of DNA run in opposite directions
- hydrogen bonds could form between certain nitrogenous bases, providing enough force to hold strands together
- Base Pairing-nearly perfect fit b/w A-T and G-C nucleotides
Before a cell divides, it duplicates its DNA in a copying process call what?
Replication
Differences between RNA and DNA
- Sugar in RNA is ribose instead of deoxyribose
- RNA is generally single stranded and not double-stranded
- RNA contains Uracil in place of thymine
Messenger RNA
RNA molecules that carry copies of instructions for assembling amino acids into proteins.
Ribosomal RNA
type of RNA that combines with proteins to form ribosomes
Messenger RNA
Type of RNA that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
Transfer RNA
Type of RNA that carries each amino acid to a ribosome during protein synthesis.
Transcription
Process by which segments of DNA serve as templates to produce complementary RNA molecules
How is RNA synthesized?
- Transcription using RNA polymerases
- Promoters-signals in the DNA molecule that show RNA polymerase exactly where to begin making RNA
- RNA Editing-introns- portions that are cut out and discarded
- exons- pieces that are spliced back together to form the final mRNA
Translation
Decoding of an mRNA to assemble amino acids into polypeptide chains
Steps of translation
- Messenger RNA is transcribed in the nucleus and then enters the cytoplasm
- Transfer of RNA-translation begins at AUG (start codon),
- each transfer RNA has an anticodon whose bases are complementary to the bases of a codon on the mRNA strand
- Polypeptide assembly line-ribosome joins the two amino acids, and breaks the bond between methionine and its tRNA. The tRNA floats away from the ribosome allowing the ribosome to bind to another tRNA. Ribosome moves along mRNA from right to left
- Completing the Polypeptide-process continues until the ribosome reaches one of the three stop codons.
Gene expression
The way in which DNA, RNA and proteins are involved in putting genetic information into action in living things
What is the central dogma of molecular biology
Information is transferred from DNA to RNA to protein
Polypeptides
Amino acids joined together into long chains
Genetic code
Collections of codons of mRNA, each of which directs the incorporation of a particular amino acid into a protein during protein synthesis
How is genetic code read?
Three letters at a time, so that each word is three bases long and corresponds to a single amino acid (each three letter word-codon)
Mutations
Heritable changes in genetic information, when cells make mistakes in copying their own DNA, inserting the wrong base or even skipping a base as a strand is put together
Types of mutations
Gene mutations: substitutions, insertions and deletions
Chromosomal Mutations
Point Mutation
Gene mutations that involve changes in one or a few nucleotides (occurs in a single point in the DNA sequence)
Frameshift Mutations
Another term for insertions and deletions (they shift the reading frame)
Mutagens
Mutations that are Chemical or physical agents in the environment
How are prokaryotic genes regulated
DNA-binding proteins in prokaryotes regulate genes by controlling transcription
Operon
A group of genes that are regulated together
Describe Operators and Promoters in the process of prokaryotic gene regulation
On one side of the operon’s three genes are two regulatory regions
- Promoter (P)-site where RNA polymerase can bind to begin transcription
- Operator (O)- where DNA-binding protein known as the lac repress or can bind to DNA
How are genes regulated in eukaryotic cells?
By binding DNA sequences in the regulatory regions of eukaryotic genes, transcription factors control the expression of those genes
Promoters have multiple binding sites for transcirption
RNA interference
miRNA silencing complex that blocks gene expression
Differentiation
Process by which cells become specialized in function and structure
Bacteriophage
A kind of virus that infects bacteria
Transformation
Process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria
Describe Darwins Theory of Evolution
- scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors
- noted that there are different, yet ecologically similar, animal species inhabited separated, but ecologically similar habitats round the globe.
- different, yet related, animal species often occupied different habitats within a local area
Artificial selection
Nature provides the variates, and humans elect those they find useful
Adaptation
Any heritable characteristic that increases an organisms ability to survive and reproduce in its environment
Fitness
How well an organism can survive and reproduce in its environment.
Natural selection
Process by which organism with variations most suited to their local environment survive and leave more offspring
(Occurs in any situation in which more individuals are born than can survive)
