BIOLOGY EXAM 4

Cell communication

cells detecting and responding to signals

What are the 2 types of cellular communication?

Intercellular signaling, Intracellular signaling

Intercellular signaling

communication between cells

Intracellular signaling

communication within cells

What are the 4 forms of signaling?

1. Autocrine

2. Direct across gap junctions

3. Paracrine

4. Endocrine

Autocrine

cell talks to itself

Direct across gap juctions

ligands pass from one cell to another through small channels

Paracrine

locally

Endocrine

long distances

What form of signaling is this?

Paracrine

What form of signaling is this?

endocrine

What form of signaling is this?

signaling across gap junctions

What form of signaling is this?

autocrine

What are the 2 types of receptors?

1. Intracellular receptors

2. Cell-surface receptors

Intracellular receptors

found in the cytoplasm

Cell-surface receptors

found on the cell surface; integral proteins

What are the 2 types of signaling molecules?

1. Small hydrophobic ligands

2. Water-soluble ligands

Small hydrophobic ligands

used with intracellular receptors; can easily cross the plasma membrane, nonpolar

Water-soluble ligands

used with cell-surface receptors; need help crossing the plasma membrane, polar

What are the 3 stages of cell signaling?

1. receptor activation

2. signal transduction

3. cellular response

Receptor activation

Signaling molecules bind to the receptor

Signal transduction

ligand binds to the receptor, signal transmitted through the membrane into the cytoplasm

What is a signaling pathway?

chain of events set off by the activated receptor

Cellular response

Different responses possible; could include programmed cell death

What is programmed cell death called?

Apoptosis

What are the 2 major phases of the cell cycle?

1. Interphase

2. Mitotic phase

What phase is when cells are not actively preparing to divide?

G0 phase

What is stage 2 of the mitotic phase?

Cytokinesis

What are cell- cycle check points?

Several points where the cell cycle stops until a go-ahead signal is received

Where do these checkpoints occur?

• Cyclins

• Cyclin-dependent kinases (Cdks)

What’s the difference between a gamete and a zygote?

Gametes are haploid and zygotes are diploid

haploid

1 set

diploid

2 sets

What are the 2 parts of meiosis?

1. Meiosis I

2. Meiosis II

What was Mendel’s model organism?

pea plants

What were the advantages of using pea plants?

• different characters

• self-fertilizing

• Large flowers to enable crossing

Character

broad, genetic feature (eye color, seed shape)

Trait

visual quality (round, blue)

P0 generation

Individuals used in first-generation crosses; true-breeding

Genotype

Underlying genetic makeup

Phenotype

Observable traits; what you can see

Gene

The basic functional unit of heredity

Allele

versions of a gene that are created by mutation and are found at the same place on a chromosome

Homozygous

Have two identical alleles for the same gene

Heterozygous

Have two different alleles for the same gene

BB

homozygous dominant

bb

homozygous recessive

Bb or bB

heterozygous

Are the parents heterozygotes or homozygotes?

Heterozygotes; Pp – one dominant, one recessive allele

What is the genotypic ratio

1:2:1; 1 homozygous dominant: 2 heterozygotes:1 homozygous recessive

What is the phenotypic ratio:

3:1; 3 purple flowers, 1 white flower

What is the dominant allele?

purple

What is the recessive allele

white

What are the alternatives to complete dominance?

1. Incomplete dominance

2. Codominance

What are the 3 laws of inheritance?

1. Law of dominance

2. Law of segregation

3. Law of independent assortment

law of segregation

Paired genes separate equally; offspring have an equal

chance of inheriting either

What is the multiplication rule?

The chance of independent events happening together is found by multiplying their chances

What is gene linkage?

Genes that are located close to each other on the same chromosome are more likely to be inherited as a pair

What is gene interaction?

A single trait is controlled by 2 or more genes

What is epistasis?

Alleles of one gene mask the expression of the alleles of another gene

What is an X-linked trait?

A gene that occurs on the X chromosome, but not on the Y

A female with a recessive, X-linked trait has a male offspring. Will he have

the trait?

Yes, if the female parent is recessive, this means that both of her X

chromosomes carry the trait

A female with a recessive, X-linked trait has a male offspring. Why or why not?

Because male offspring only get 1 X and inherit the trait 100% of the time

What is the probability that the female offspring of the same parent will

have this trait?

50%, but may get a dominant X chromosome from male parent

What is this offspring called?

a carrier