Semester 2 Final Exam Study Flashcards

Gene

Unit of heredity which is transferred from a parent to an offspring

Allele

One of 2 or more alternative forms of a gene

Homozygous

Having two identical alleles for a particular gene

Heterozygous

Having two different alleles for a particular gene

Haploid

Having a single set of unpaired chromosomes, typical of gametes

Diploid

Having two complete sets of chromosomes, typical of somatic cells

Gamete

A reproductive cell that contains a haploid set of chromosomes, either sperm or egg in animals

Ecology

The study of interactions between organisms and their environment

Trophic Level

Each step in an ecological pyramid

Weather

Day to day conditions

Climate

Year to year, average conditions

Biotic Factors

Any living part of an ecosystem

Abiotic Factor

Any non living part of an ecosystem

Habitat

Where an organism lives (“address”)

Mutation

Random changes in DNA

Evolution

The change in the heritable characteristics of biological populations over successful generations

Gene pool

All the genes including all the different alleles for each gene that are present in a population at any point in time

Genetic Drift

Random changes in allele frequencies

Speciation

One species splits into 2 or more species

Natural Selection

A process of the survival of the fittest

Artificial Selection

Selective breeding of plants and animals to promote the occurrence of desirable traits in offspring

Autotroph

Any organism that makes its own food using energy from the sun

Heterotroph

Any organism that relies on other organisms for food

Climate Change

Changes in average temperature

Prophase

Metaphase

Anaphase

Telophase

Process of Interphase

G1 phase - Cell growth

S phase - DNA replication (synthesis)

G2 phase - Final Preparation for division

Why do cells have to divide?

Growth: To allow an organism to get larger

Repair: To replace damaged or dead cells

Efficiency: As a cell grows, its volume increases faster that its surface area.

What is Mitosis?

A type of cell division

• Results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus

Division of the Nucleus

• Prophase, Metaphase, Anaphase, Telophase

• Cytokinesis: Division of the cytoplasm, resulting in two separate daughter cells

When do chromosomes become visible during the cell cycle?

During Prophase

• When loose chromatin condenses into tightly coiled structures we recognize as chromosomes

Chromosome Anatomy

What is the role of spindle fibers?

They attach to the centromeres of the chromosomes and pull the sister chromatids apart toward opposite poles of the cell

What are factors that affect the rate of mitosis?

• Cell Type

• Environment

• Injury

• Cell size

What is centriole?

Cylinder shaped organelle found in animal cells

• They move to opposite ends of the cell and help organize the spindle fibers that pull the chromosomes apart

Stage of Meiosis 1 Description

• Prophase 1: Chromosomes condense, crossing over occurs

• Metaphase 1: Homologous pairs line up in the middle of the cell

• Anaphase 1: Pairs are pulled apart to opposite ends of the cell

• Telophase 1: Cytokinesis, cell divides into 2 cells (each cell now having half the number of chromosomes)

Stage of Meiosis 2 Description

Prophase 2: Chromosomes condense again in the two cells

Metaphase 2: Chromosomes line up in the middle (single file)

Anaphase 2: Sister Chromatids are pulled apart

Telophase 2: Cytokinesis, both cells divide (resulting in 4 unique haploid cells)

What are homologous chromosomes?

Pairs of chromosomes (one from each parent) that are similar in size, shape, and the specific genes they carry

What is crossing over? When does it occur?

Exchange of genetic material between homologous chromosomes (creates genetic variety)

• occurs in Prophase 1 of Meiosis

What type of cells go through meiosis? What do we know about the cells at the end of Meiosis?

Cell Type: Only germ cells (creates gametes like sperm & egg cells) go through Meiosis

Result: 4 daughter cells (each cell is haploid, has half the DNA of the original cell, and is genetically unique)

How do you calculate Diploid and Haploid cells?

Diploid = Haploid x 2

Haploid = Diploid / 2

How many rounds of Interphase and cell division are there in Meiosis?

Interphase: only 1 round (DNA replication happens only once before the whole process starts)

Cell division: There are 2 rounds of division (Meiosis 1 and Meiosis 2)

Mendel Trait Punnet Squares

Standard version where one allele is dominant and masks the recessive one

• B - If this is present, it masks the recessive traits

• bb - Only recessive if both are lowercase

ex)

B = Brown eyes

b = Blue eyes

Bb = Brown eyes

Incomplete Dominance Punnet Squares

No allele is truly dominant over the other (heterozygous phenotype is a mix of the 2 homozygous phenotypes)

ex)

RR = Red flower

WW = White flower

RW = Pink flower

CoDominance Punnet Squares

Both alleles are expressed equally and at the same time (both traits show up in the heterozygous individual; they don’t mix)

ex) A black chicken crossed with a white one produces a chick w/ both black and white feathers

Sex Linked Traits