Biology Final (Study Guide)

Asexual Reproduction

One cell replicates genetic material and splits into two, offspring are genetically identical to parent, offspring arise from parent

Sexual Reproduction

Genetic makeup comes from 2 parents, offspring are genetically diverse from each other and parents

Gametes

Sex cells produced through meiosis, Sperm- Male, Egg- Female

Mitosis

Cellular division that produces 2 genetically identical nuclei (cells)

Meiosis

Cellular division that splits the number of chromosomes in half, yielding genetically diverse/variable nuclei (cells)

Fertilization

The union of two gametes producing a zygote

Apoptosis

Programmed cell death, shapes new structures with cell division

Chromosomes

A long DNA molecule wrapped around the proteins in the nucleus; genetic material of eukaryotes/eukaryotic cells

Genome

All the genetic material in an organism

Why is DNA replication called semi-conservative?

DNA replication is considered semi-conservative due to the keeping of one strand of parent/original DNA

What is the role of Primase during DNA replication?

Primase adds short RNA primer to the template strand

What are the events of Binary Fission?

-DNA replicates and attaches to the cell membrane

-The cell membrane grows between the DNA molecules separating them creating new cell wall material

-2 daughter cells with identical DNA to the parent are formed

State the function of mitosis in multicelled eukaryotes and in single celled organisms

-In single celled organisms, mitosis is used to duplicate/give rise to daughter cells/offspring

-In multicelled eukaryotes, mitosis is used for organism growth/development, and repairing of tissues

Identify specific bodily cells where mitosis is likely to be occurring

Somatic cells such as skin cells, hair follicle cells, epithelial cells, and in rapidly dividing cells

Describe the Cell Cycle (G1)

Cell grows and functions normally, protein synthesis occurs

Describe the Cell Cycle (S)

Cell replication of entire genome/every chromosome

Describe the Cell Cycle (G2)

Cell produces needed proteins for mitosis

Describe the Cell Cycle (Prophase)

Chromosomes condense, spindles form as centrosomes, nuclear envelope breaks down, spindle fibers attach to kinetochores

Describe the Cell Cycle (Metaphase)

Chromosomes line up in the center of the cell

Describe the Cell Cycle (Anaphase)

Chromatids are separated by spindle fibers pulling them apart

Describe the Cell Cycle (Telophase)

2 nuclei form after splitting, spindles disappear

Describe the Cell Cycle (Cytokinesis)

The 2 nuclei split into two different cells

Describe the events associated with each phase of mitosis (Prophase)

Chromosomes condense and become visible, spindle is formed as chromosomes move to opposite ends, nuclear envelope breaks up, spindle fibers attach to kinetochores on chromosomes

Describe the events associated with each phase of mitosis (Metaphase)

Chromosomes line up on the equator of the cell

Describe the events associated with each phase of mitosis (Anaphase)

Sister Chromatids separate and move to opposite poles/ends of the cell

Describe the events associated with each phase of mitosis (Telophase)

Nuclear envelope and nuclei form at each end of the cell, chromosomes decondense and spindles disappear

Describe the division of the cytoplasm (cytokinesis) in plant and animal cells (Plant)

The vesicles within a plant cell separate the two newly formed nuclei, the cell membrane contracts, proteins contract like drawstrings

Describe the division of the cytoplasm (cytokinesis) in plant and animal cells (Animal)

A cleavage furrow appears during telophase deepening a ring of proteins , which is an indentation of the cell membrane

Compare and contrast sexual and asexual reproduction (Sexual)

Genetically variable offspring, genetic makeup from 2 parents, increased survival due to adaptations

Compare and contrast sexual and asexual reproduction (Asexual)

Genetically identical offspring, genetic makeup from one parent, variation only through mutation

Distinguish between autosomes and sex chromosomes (Autosomes)

Chromosome pairs 1-22, non-sex chromosomes

Distinguish between autosomes and sex chromosomes (Sex Chromosomes)

-Pair 23, carries genes that determine sex

-XX: Female

-XY: Male

Describe the role of homologous chromosomes in sexual reproduction

Homologous chromosomes are pairs of chromosomes from each parent that encode for the same gene but may have different alleles ensuring genetic diversity. They are also responsible for passing on genetic information from one generation to the next

Differentiate between diploid and haploid cells (Diploid)

2n, two complete sets of chromosomes, zygotes, somatic cells

Differentiate between diploid and haploid cells (Haploid)

n, one complete set of chromosomes, germ cells such as sperm or egg cells

List and explain three ways that meiosis generates genetic variability among offspring (Crossing Over)

2 homologous chromosomes exchange genetic material during prophase I leading to new gene combinations

List and explain three ways that meiosis generates genetic variability among offspring (Independent Assortment)

Chromosome pairs randomly align during metaphase I creating new and random genetic pairings

List and explain three ways that meiosis generates genetic variability among offspring (Fertilization)

Combinations of random chromosomes through fertilization of the joining of two random gametes (sperm and egg cells) produce variability

Compare and Contrast Meiosis and Mitosis (Meiosis)

-Produces 4 haploid gametes

-Genetically variable

-Germ Cells/Gametes

-One S Phase/ 2 nuclear divides

Compare and Contrast Meiosis and Mitosis (Mitosis)

-Genetically identical

-Produces 2 diploid daughter cells

-Occurs in somatic cells

-One S phase/nuclear division

Explain how polyploidy and nondisjunction can lead to missing or extra chromosomes in a gamete (Polyploidy)

Has one or more complete sets of extra chromosomes, 3n: Triploid, 4n: Tetraploid, etc.

Explain how polyploidy and nondisjunction can lead to missing or extra chromosomes in a gamete (Nondisjunction)

When chromosomes fail to separate during anaphase I or II, Spindle fibers may not attach to a chromosome or form properly. This results in a sperm/egg cell with two copies of a chromosome or none at all

Compare and Contrast Gamete formation in a man and a woman (Woman)

Polar bodies produced play no further role in reproduction, resulting in one mature gamete and three polar bodies. Gametes formed through oogenesis.

Compare and Contrast Gamete formation in a man and a woman (Man)

Results in 4 haploid gametes called spermatids. Gametes formed through spermatogenesis.

Mendel's Law of Segregation

Two alleles of each gene are packaged into separate gametes; they segregate during gamete production

Mendel's Law of Independent Assortment

During gamete formation, alleles for one gene do not influence the alleles for another gene (Segregation of alleles)

Genes

A portion of DNA/sequence that encodes a specific protein

Alleles

Different variations/variants/types of a gene

Diploid

2n, has two complete sets of chromosomes

Haploid

n, has one complete set of chromosomes

Hybrid

When a cross produces a mix of offspring for one or multiple traits; Heterozygous offspring

True Breeding

When a cross produces offspring with traits identical to the parents for one or multiple traits; Homozygous offspring

Homozygous

An organism that has two identical alleles for a trait/gene

Heterozygous

An organism that has two different alleles for a trait/gene

Genotype

An organism's genetic makeup, or allele combinations

Phenotype

The physically present/visible characteristics of an organism

P Generation

Parental generation, the first two individuals that mate in a genetic cross

F1 Generation

Filial generation, first generation of offspring of the P generation

F2 Generation

Offspring of F1 generation

What is a test cross?

A test cross is a cross between an individual of an unknown genotype and a homozygous recessive individual

When is a test cross used?

It is used for determining unknown genotypes of organisms with dominant phenotypes

Codominance

Two completely expressed alleles in a heterozygote (Different alleles)

Incomplete Dominance

A heterozygotes phenotype displays a mix of phenotypes from 2 homozygotes

Epistasis

When the result of one gene effects the other gene's expression

Pleiotropy

When one gene has multiple effects on another genes phenotype, which can possibly switch biochemical pathways

Multiple Alleles

Refers to the existence of more than 2 alleles in a particular gene within a population, individuals only carry 2

Define Linkage Groups

A set of genes close together on the same chromosome that are typically inherited together

Self Fertilizing

Occurs when an organism uses its own gametes for fertilizing resulting in offspring with a mix of the parents genes

Cross Fertilization

The combination of sex cells from different individuals of the same species creating variable offspring

X-Linked Dominant

Very few disorders are caused by X-Linked Dominant traits; Extra hairiness, Retinitis Pigmentosa, Hypophosphatemic Rickets

X-Linked Recessive

Affects more males than females since men only have one X so the trait cannot be masked, more disorders are X-Linked Recessive; Hemophilia A, Red-Green Colorblindness, Duchenne Muscular Dystrophy

Steps Required to make a Transgenic Organism?

-Acquire source DNA and a cloning vector

-Cut source and vector DNA with the same restriction enzyme

-Mix donor DNA and vector DNA

-Insert recombinant DNA into recipient cells

What is PCR?

Polymerase Chain Reaction, rapidly produces millions of DNA clones/copies of a selected sequence

Process of PCR?

- denaturation (95): denature template DNA by heat, strands separate

- annealing (55): cool to allow primers to bind to sequences on single stranded DNA

- extension (72): DNA polymerase adds nucleotides to 3' end of each primer

What is the purpose of DNA sequencing?

DNA sequencing is used to determine the order of nucleotide bases in a DNA segment and deducing protein sequences finding evolutionary relationships among species

Temperatures for DNA sequencing?

Denaturation: 94-98°C

Annealing: 50-65°C

Extension: 72°C

What does STR stand for?

Short Tandem Repeats, short repeated sequences of DNA

Describe DNA profiling techniques

DNA profiling techniques are STR analysis, identifying individuals through short repetitive DNA sequences

Stem Cells

Special because they can develop into different types of cells, undifferentiated

Differentiated Cells

These are cells which have become modified and specialized within an organism, they can only carry out one singular function

Embryonic Stem Cells

Can give rise to all cell types within the body, totipotent, located in fertilized eggs

Adult Stem Cells

Differentiate into a limited number of cell types, pluripotent

Steps of Somatic Cell Nuclear Transfer

-Obtain donor cell nucleus

-Remove nucleus from egg donor cell

-Fuse denucleated egg w/ nucleus

-Cell divides to form an embryo

-Embryo is transferred to surrogate mothers uterus

Cloning vs. Sexual Reproduction

Cloning does not involve the fusion of a sperm and egg cell, offspring are genetically identical to their parents, requires one cell

How DNA probes help biologists locate specific DNA sequences

If the DNA probes are bound to the DNA then the disease is present; If the probes didn't bind to the DNA then the disease was not present. The tag on the DNA probes will reveal it's location

Preimplantation Genetic Diagnosis (PGD)

Usage of DNA probes to detect genetic illness in an embryo before implanting it into a uterus

Genetic Testing

Can detect existing diseases; tests detect the alleles in DNA cells taken from blood, saliva, or bodily tissues. Same genetic tests as PGD, only with alleles

Gene Therapy

Replacement of a faulty gene with a functional version of a gene within a cell

How genetic information is passed down from one generation to the next

Genetic information is contained in genes carried by chromosomes in the nucleus, which are divided and passed on through meiosis/sexual reproduction

Role of Meiosis in Sexual Reproduction

A diploid cell divides twice to create 4 haploid nuclei, reducing the chromosome number by half, creating new allele and genetic combinations

Role of Gamete Formation in Sexual Reproduction

Packages the haploid chromosomes into reproductive cells

Role of Fertilization in Sexual Reproduction

Merges haploid gametes from both parents producing a diploid zygote with genetic material from both parents, genetically variable

Somatic Cells in Sexual Reproduction

All other diploid body cells that can't undergo meiosis/sexual reproduction

Germ Cells in Sexual Reproduction

Can undergo meiosis to produce 4 genetically variable haploid gametes

Autosomal Dominant

Only one copy of the mutated gene (from either parent) is needed to express the trait or disorder.

Affected individuals have a 50% chance of passing the gene to their offspring.

Typically, the disorder appears in every generation.

Both males and females are equally affected;

Huntington's Disease, Achondroplasia

Autosomal Recessive

Two copies of the mutated gene (one from each parent) are needed to express the disorder.

Both parents must be carriers (having one copy of the mutation) for the child to be affected.

The disorder often appears in siblings, but not usually in every generation.

Both males and females are equally affected;

Cystic Fibrosis, Sickle Cell Anemia

Steps of DNA replication

1. Unwinding:

Helicase unwinds the DNA, separating the two strands.

2. Priming:

Primase adds a short RNA primer to start the copying process.

3. Building New Strands:

DNA polymerase adds new DNA pieces (nucleotides) to build the new strands.

On the leading strand, DNA is copied smoothly in one go.

On the lagging strand, DNA is copied in small chunks called Okazaki fragments.

4. Replacing RNA Primer:

DNA polymerase I removes the RNA primers and replaces them with DNA.

5. Sealing:

DNA ligase joins the small chunks (Okazaki fragments) on the lagging strand to make it continuous.

6. Completion:

The process ends when both strands are fully copied.

Functions of Enzymes involved in DNA replication

Helicase: Unwinds double helix

Binding Proteins: Stabilize each strand

Primase: Adds short RNA primer to template strand

DNA Polymerase: Binds nucleotides to form new strands

Ligase: Creates covalent bonds between adjacent DNA segments

What are Ti Plasmids?

Tumor inducing plasmids

How are they used to create transgenic plants?

Ti plasmids are modified to carry useful genes and introduced into Agrobacterium bacteria, which then infect plant cells and transfer the modified DNA. The transformed plant cells grow into full plants with the new traits, creating transgenic plants