Biology Final 2nd Semester

Homologous

Chromosomes in which one set comes from male parent and one from female

Diploid

Cell that contains two sets of homologous chromosomes

Haploid

Cell that contains only a single set of genes

Tetrad

Structure containing four chromatids that forms during meiosis

Crossing-over

Homologous chromosomes exchanging portions of their chromatids during meiosis

Chromosomes

Structure in nucleus that contains genetic info passed from one generation to another

Chromatids

One of two identical sister parts of a duplicated chromosomes

Centromere

Region of a chromosome where two sister chromatids attach

Centriole

Structure in animal cell that helps organize cell divison

Gametes

Sex cell

Genetics

Scientific study of heredity

Trait

Specific characteristic of an individual

Gene

Sequence of DNA that determines a trait

Allele

One of a number of different forms of a gene

Probability

Likelihood that a particular even will occur

Homozygous

Having two identical alleys for a particular gene

Heterozygous

Having two different alleles for a particular gene

Dominant

Genetic characteristic that is expressed when they carry at least one copy

Recessive

Genetic characteristic that only appears when an individual inherits two copies of gene

Genotype

Genetic makeup of an organism

Phenotype

Physical characteristics of an organism

Incomplete Dominance

Situation in which one allele is not completely dominant over another

Codominance

Both phenotypes produced by both alleles are completely expressed

Genome

Entire set of genetic info that an organism carries in its DNA

Karyotpe

Micrograph of diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size

Autosomes

Chromosome that is not a sex chromosome; also called autosomal chromosome

Sex Chromosomes

One of two chromosomes that determines an individual’s sex

Pedigree

Chart that shows presence or absence of a trait according to relationships within a family across generations

Trisomy

Genetic condition characterized bu presence of three copies of a specific chormosome

Bacteriophage

Kind of virus that infects bacteria

DNA

Genetic material that organisms inherit from their parents

Nucleotides

Subunit which nucleic acids are composed of

5 carbon sugar, phosphate group, nitrogenous base

Base pairing

Principle that bonds in DNA can form only between adenine and thymine and guanine and cytosine

Replication

Process of copying DNA prior to cell divison

DNA polymerase

Principle enzyme involved in DNA replication

RNA

Single stranded nucleic acids that contains sugar ribose

Transcription

Synthesis of an RNA molecule from a DNA template

Translation

Sequence of bases of an mRNA is converted into the sequence of amino acids of protien

RNA Polymerase

Enzyme that links the growing chain of RNA nucleotides during transcription using a DNA strand as a template

Polypeptides

Long chain of amino acids that makes proteins

Codon

Group of 3nucleotide bases in mRNA that specify a particular amino acid to be incorporated onto a protein

Classification

Scientific system used to group and categorize all living and extinct organisms

Taxonomy

System of naming and classifying organisms based on shared characteristics and universal rules

Binomial Nomenclature

Classification system in which each specifies is assigned a two-part scientific name

Phylogeny

Study of evolutionary relationships among organisms

Dichotomous Key

Tool used to identify unknown organisms or objects based on their observable traits

Prokaryotes

Unicellular organism that lacks a nucleus

Binary Fission

Asexual reproduction in which organism replicates DNA and divides in half, producing two identical daughter cells

Pathogen

Disease-causing agent

Chitin

Complex carb that makes up cell walls of fungi

Hyphae

Branching, threadlike filaments that make up main vegetative body of fungus

Mycorrhizae

Symbolic association of plant roots and fungi

Mycelium

Densely branched network of hyphae of fungus

Lichen

Symbiotic association between a fungus and a photosynthetic organism

Monocot

Angiosperm with one seed leaf in its ovary

Dicot

Angiesperm with two seed leaves in ovary

Vascular Tissue

Specialized tissue in plants that carries water and nutrients

Xylem

Vascular tissue that carries water upward from roots to every part of the plant

Phloem

Vascular tissue that transports solutions of nutrients and carbs produced by photosynthesis through the plant

Gymnosperm

Group of seed plants that bear their seed directly on scales of cones

Angiosperm

group of seed plants that will bear their seeds within a layer of tissue that protects the seed; also called flowering plant

Pollination

Transfer of pollen from the male reproductive structure to the female reproductive structure

Transpiration

Loss of water from a plant through its l;eaves

Cladogram

Diagram depicting patterns of shared characteristics among species

Invertebrates

Animals that lacks a backbone or vertebral column

Chordates

Animal that has for at least one stage of its life, a dorsal, hollow nerve cord, notochord, a tail that extends beyond the anus and pharyngeal pouches

Vertebrates

Animal that has a backbone

Coelom

Body cavity lined with mesoderm

Cephalization

Concentration of sense organs and nerve cells at the anterior end of an animal

Dorsal

top, upper side of an animal

Ventral

Belly or underside of the animal

Anterior

Front or head end of an animal

Posterior

Rear or tail end of an animal

What is mitosis?

The process by which cells replicate

Why do cells undergo mitosis?

So all our genetic material is passed on to future cells, and to grow

What happens in each part of interphase?

HAPPENS IN INTERPHASEIn

G1→ cell grows, organelles are produced, longest phase, checks if conditions are right to divide, “decides to divide or not”

S→ DNA replicates, each chromosome is duplicated (cell has double DNA), ends w two identical sister chromatids

G2–> cell grows, synthesizes proteins, organelles duplicate, makes spindle fibers

What occurs during stages of mitosis

Interphase: “resting phase”, cell grows and prepares for division, DNA is replicated

Prophase: DNA condenses into chromatids, sister chromatids attach at centromere, centrioles move to opposite ends of the cell, form asters and spindles, micro tubules connect to centromere and pole to pole, nuclear envelope starts to disappear

Metaphase: Spindles line chromosomes up at the metaphase plate, called homologous chromosomes that later seperate

Anaphase: Microtubles move homologous chromosomes apart to opposite ends of the cell (each side now has one sister chromatid), results in 2 complete sets of DNA

Telophase: Asters and spindles disassembled and taken down, nuclear envelope beings to form around each set of chromosomes, chromosomes unwind, cell membrane/wall forms by cytokinesis

How does mitosis differ between animal and plant cells?

Plants: no centrioles, cell plate forms in middle and grows outward, no aster fibers

Animals: cell membrane pinches inward, no cell wall

Describe how cancer and tumors happen?

cells that never stop going through mitosis

Most errors occur in s phase in interphase but G2 doesnt catch it

What is the purpose of meiosis?

Form of cell divison that ultimately creates sex cells

What are similarities and differences between mitosis and meiosis?

Mitosis→ EXACT copy

Meiosis→ sex cells w half the DNA

similarities: Start with cell w full set of chromosomes, undergo same phases

differences:

Mitosis→ one round of division, two identical cells, ends with 46 chromosomes

Meiosis→ two rounds of division, ends w four unique cells, ends w 23 chromosomes

What are the four stages of Meiosis I and Meiosis II? What happens in each stage

Prophase 1→ chromosomes appear+coil up, spindle forms, chromosome pair comes together with another creating a tetrad, nuclear envelope disappears, crossing over may occur

Metaphase 1→ pairs of homologous chromosomes move to the middle of the cell as centromeres attach to the spindle fiber

Anaphase 1→ one chromosome from each homologous pair of chromosomes move to opposite poles of cell

Telophase 1→ two nuclear envelopes surround the separate chromosomes and cytokinesis may occur, interkinesis will follow, a resting period from Telophase I to Prophase II

Prophase II→ each chromosome is composed of a pair of sister chromatids connected by a centromere

Metaphase II→ chromosomes are lined up at a equator by spindle fibers

Anaphase II→ centromeres divide and chromosomes migrate to the poles

Telophase II→ nuclear envelope forms, cytoplasm divides, spindle disappears

When does crossing-over occur? How does this increase genetic diversity?

Prophase I of Meiosis

When homologous chromosomes pair up to form a tetrad

Mixes mom and dad’s DNA together on same chromosome so you have chromosomes that are neither fully mom nor dad

Why is it important for meiosis to result in haploid sex cells?

Because two cells combine so if it was diploid you would end up with 92 cells

What is the first cell of a new individual or a fertilized egg cell called? How many chromosomes does it have?

Zygote

46 chromosomes, 23 homologous chromosomes

Who was Gregor Mendel? What organism did he use to study genetics?

Monk who figured out traits are passed from parents to offspring

Used pea plants bc they grew fast, produced lots of offspring and had easily obersable traits

What doe P1, F1 and f2 represent in genetic crosses?

P1→ grandparents

F1→ parents

F2→ kids

What is a Punnett Square? What is the difference between a monohybrid and dihybrid cross?

Grid used to predict traits offspring might inherit from their parents

Mono→tracks one trait, 2×2 Punnett square

Dihybrid→ tracks two traits, 4×4

What does Independent Assortment mean?

Genes for different traits are passed down to offspring independent of each other, one trait being inherited has no effect on how another trait is inherited

What is the difference between incomplete dominance and codominance? Examples of each

Incomplete dominance→ offspring shows an intermediate phenotype between the parents

Ex: red+white=pink

Codominance→Offspring shows both alleles

Ex: red+white=red and white (RW)

How can a phenotype be altered to be different than the genotype would determine? Person could do/environment impact a physical trait

Weightlifting can change the muscle size and your body shape, sun exposure can change skin color

Many animals coats change in winter such as artic foxes, flamingos colors change because of the food they eat

Which choromosomes are autosomes and which are the sex chromosomes?

Autosomes→ 44 chromosomes in your body, carry genes for regular traits (hair color, eye color, height, disease risk)

Sex chromosomes→ pair #23, 2 chromosomes, determine biological sex (mom can only give X, dad can give X or Y)

What is a sex-linked trait?

Trait whose gene is located on sex chromosomes not autosome

Ex: colorblindness

What is nondisjunction? When does it happen and what is the result?

When chromosomes fail to separate properly during cell divison

Happens in meiosis I, meiosis II or meiosis

Result: cell ends up with wrong number of chromosomes (one less of one extra chromosome)

Who is Frederick Griffith? What tests did he perform?

British biologist, studied two forms of bacteria, one cause pneumonia in mice, other was harmless, when pneumonia was heat treated mice lived, when harmless and heat treated bacteria were mixed the mice died.

What was the Hersey and Chase experiment?

Put radioactive sulfur and phosphorus in viruses

Phosphorus went into DNA and sulfur didn’t

DNA carries genetic info

Which scientists demonstrated the structure of DNA as a double helix?

Watson and Crick

How did Rosaline Franklin contribute to understanding the structure of DNA?

Studied structure of DNA using X-rays

Proved DNA had a spiral shape, two strands were present

What is the basic structure of a nucleotide?

Ring shaped sugar called deoxyribose

Phosphate group

Nitrogenous base

What are the four different types of nitrogenous bases that compose DNA?

Adenine, thymine, cytosine, guanine