sem2 biology

Meiosis 1

First round of cell division in meiosis, reduces cells chromosomes from diploid to haploid

Meiosis 2

Second round of cell division, separated sister chromatids

Prophase 1

Chromosomes condense and pair up with homologous partners, crossing over happens

Metaphase 1

Paired homologous chromosomes align in the middle

Anaphase 1

Homologous chromosomes pulled apart towards ends (sister chromatids still attached at centromere)

Telophase 1

Nuclear membrane around each set of chromosomes

Prophase 2

Nuclear envelope disappears, no crossing over happens, chromosomes condense again

Metaphase 2

Individual chromosomes align in middle

Anaphase 2

Centromeres split and pulled away

Telophase 2

Nuclear envelope reform

Haploid

Cells with two sets of chromosomes

Diploid

Cells with one set of chromosomes

Homologous chromosome

Matching pairs of chromosomes, one from each parents

Gamete

Sex cell

Zygote

Initial single cell formed when two gametes fuse during fertilization

Fertilization

Sexual reproduction between female and male gametes

Somatic cells

Body cells

Crossing over

Exchange of genetic info between paired homologous chromosomes during meiosis

Nondisjunction

Failure of paired chromosomes to separate properly, leads to Down syndrome (extra chromosome)

Sex chromosomes

45 chromosomes (23 pairs), first 22 are autosomal and 1 is sex cell, XX is female and XY is male

Autosomes

Body cell

Karyotype

An individuals complete set of chromosomes

Sex linked vs autosomal

Sex linked is mostly males and skips gen, autosomal goes for both genders and every gen

Okazaki fragments

Short newly synthesized segments of DNA formed on lagging strand during DNA replication

DNA

Double helix made of nucleotide bases which carry genetic information

Chromosome

Composed of proteins and dna, thread like structure

Chromatin

Mixture of dna that forms chromosomes

Chromatid

One half of a replicated chromosome

RNA

Single strand nucleic acid as messenger between dna and ribosomes to produce proteins, made of bases with U

Nucleic acid

Chains of nucleotides that makes up DNA and RNA

Nucleotide

Monomer of nucleic acid with nitrogenous bases, phosphate group, and sugar

Sugar with ribose and deoxyribose

Sugar can be ribose in RNA with U and deoxyribose in DNA with bases ATCG

Adenine

goes with thymine

Thymine

Goes with adenine

Cytosine

Goes with guanine

Guanine

Goes with cytosine

Uracil

Only with RNA, goes with adenine and takes thymine place

Hydrogen bonds

Holds base pairs together

Complementary base pairing

A to T and C to G

Antiparallel

Parallel but in opposite direction, orientation of phosphate sugar backbones

Amino acid

Are coded by codons in during protein synthesis

Polypeptide

Chain of amino acids linked by peptide bonds

Protein

Chains of polypeptides

DNA vs RNA

DNA: double helix, deoxyribose sugar, with T, for genetic info

RNA: single strand, ribose sugar, with U, for protein synthesis

Famous experiments showing dna as molecule of heredity

Hershey chase experiment: 2 viruses one with dna and one with protein, only dna entered bacteria to make more viruses

Helicase

Unwinds dna into two strands during dna replication

DNA polymerase

Synthesizing new dna strands by adding nucleotides (ATCG) to the template stranded

Ligase

Joins DNA fragments by repairing breaks in sugar phosphate backbone

Template strand

The original dna strand

Semi conservative

half new and half old of the dna

Basic steps of DNA replication + purpose

Initiation, elongation, termination; replication of DNA

RNA polymerase

Creates a rna molecule from dna strand, starts transcription process

mRNA

Single stranded molecule carrying genetic material instructions from dna in nucleus to cytoplasm for protein synthesis

tRNA

Translates genetic code from mRNA into proteins by paring anticodons with complementary mRNA codon

rRNA

Binds with proteins to create ribosomes by translating mRNA into amino acids

Intron

Non coding regions removed by RNA splicing

Exon

Coding dna/rna segments that are translated into proteins

Codon

On mRNA coding for amino acids

Anticodon

On tRNA and complementary nucleotide sequence that binds to mRNA to get correct amino acid

Transcription of DNA to RNA

RNA polymerase attaches to promoter region (binding site) of DNA, builds up RNA molecule, detach from DNA and becomes mRNA

Edits to RNA before leaving nucleus

Slice of introns

Translation of mRNA to protein

tRNA molecules match amino acids to mRNA codons to make amino acids

Point mutation

Is a change to DNA base pair or RNA sequence (an insertion, deletion, sub, silent)

Frameshift mutation

Insertion or deletion of nucleotides

Insertion

Adding of another base pair

Deletion

Getting rid of a base pair in DNA

Silent

Sub but the amino acid doesn’t change

Missense

Change in DNA with diff amino acid

Nonsense

Premature stop codon

Descent with modification

Passing of genetic traits to offspring across generations; with ancestor and diversity

Artificial selection

Intentionally breeding animals/plants for specific traits leading to genetic changes in those species over generations

Sexual selection

Form of natural selection, individuals with specific traits are more successful at obtaining mates+reproduction

Fossil record

In rock layers, showing fossils with oldest at the bottom

Fossil

Preserved remains of once living organisms

transitional species

An organism with intermediate traits, gap between ancestors and descendants

Homology

Similarities resulting from common ancestry

Structural/anatomical homologies

Physical features shared by different species deriving by a common ancestral

Molecular homologies

Similarities in DNA due to common ancestors

embryonic homolgies

Similarities in the embryos among different species that come from common ancestors

Vestigial structures

Remnants of features that served important functions in the organism’s ancestors

Sources of variation

Genetic (inherited), environmental (non/inherited), combined

Heritable vs non heritable traits

heritable: genetic dna from parent to offspring (eye color, blood type)

non heritable: acquired through organism lifetime by environment (skills, behaviors)

Adaptation

Heritable trait that improves organism chance of survival and reproduction in environments

Darwin’s observations from his voyage

1. tortoise and finches vary by island, adapt to local foods

2. Discovered fossils (connections between extinct + modern species)

Natural selection

Process where organisms better adapted to environment tended to survived + produce more

Conditions of natural selection

Variation, inheritance, survival/reproduction differential, adaptation to environment

takeaways natural selection

1. Populations evolve, individuals do not

2. NS can amplify or diminish genetic traits

3. No goal, doesn’t lead to perfect adaptation

descent with modification

passing of genetic traits from parent to offspring with small heritable changes over generations

artificial selection

intentionally breeding organisms by humans to make specific phenotypes

sexual selection

form of natural selection where organisms with certain heritable traits are more successful at reproduction and obtaining mates

fossil record

collection of fossils and their placement in earths strata

transitional species

organisms with traits common to ancestors and descent group

structural/anatomical homologies

similar physical features like bones found in different species that were inherited from a common ancestor

molecular homologies

similarities in DNA sequences or amino acids between different organisms showing common ancestry

embryonic homologies

similarities in structural developments in embryos across different species

vestigial structures

anatomical features that have lost their function which their ancestors used

sources of variation

differences of phenotypes from 1.mutation 2.meiosis 3.gene flow 4.random fertilization

heritable/non heritable traits

heritable: genetic traits (eye color)

non heritable: acquired during lifetime (language)

adaptation

evolutionary process that enhances an organisms survival and reproduction in a specific environment

Darwin’s observations

finches beaks difference in islands, tortoise shell color, fossils resembling current organisms